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"No one realized it would prove addictive. But it did. Terribly addictive. And over time, the continued ingestion of it began to eliminate the Yeerks' need for Kandrona rays. At the same time, it drove them crazy. You see, it seems to literally replace some of a Yeerk's brain stem."
"What is the food, Mr. Edelman?"
"Oatmeal. But only the instant kind. And then, only the maple and ginger flavor."
George Edelman and Rachel[src]

The Underground, published in March 1998 and written by K.A. Applegate and Michael Grant, is the seventeenth book in the Animorphs series. It is the fifth book narrated by Rachel and her fourth book as sole narrator.


Official Description

What's tasty, good for you, and only takes sixty seconds to make? Oatmeal. And it's making the Yeerks more than a little crazy. Now Rachel, the other Animorphs, and Ax have a new weapon against the Yeerks. Sounds good, right?

Wrong. Because it means another trip to the Yeerk pool. And the possibility of running into Visser Three. And of not being able to get back up to the surface. The Animorphs and Ax have taken chances before and been very lucky. But this time their luck may be about to run out...

Plot Summary

This section needs a rewrite

The Animorphs are walking through the woods after getting a half day at school, Rachel and Marco are trying to convince Jake to use their powers to help Ax better understand more about Earth's culture, when, in reality, a new Planet Hollywood is opening in town, but they can't get tickets, so they want to use their powers to gain access to the event. Rachel really wants to be there for the fashion show featuring outfits by Ralph Lauren and Marco is able to convince Jake to go by telling him Shaquille O'Neal will be there.

Later that night, the Animorphs are at the waterfront in their in their bird-of-prey morphs, flying high in the sky, and watching the outdoor event with their superior eyesight. As Rachel wheels around in a huge circle, which carries her closer to a skyscraper called the Kenny Building, she sees a man in an empty office on the next to highest floor, who picks up a chair and throws it at the window, shattering it. Rachel warns the others, which Cassie was aware of as well, that the man was going to commit suicide. They fly towards the window just as the man runs straight out and begins plummeting towards the ground. Rachel grabs the man with her talons, but is dragged along with him, so she opens her wings which slows them down, but not by much. Tobias then swoops down and grabs the man's left arm, and Jake comes in grabbing the back of the man's collar. Tobias instructs them to glide towards the water, not flap towards it.

Cassie, Ax, and Marco then arrive as Tobias tells them to line their wings at an angle for a level glide. The man then begins falling slower, but not quite enough to survive. As the Animorphs in bird morph and the man reach the water's edge, they let the man go. As soon as they do, the man falls into the water and Rachel sees that he is now stuck in the mud at the bottom of the river. She dives down towards the water, but can't fly out of the water. She quicky demorphs, swims to the surface to get some air, and begins morphing into dolphin. She heads back for the man, who had fought his way out a little, but not enough, and was now limp and motionless. Rachel buries her snout in the small of his back, bends him backwards, and kicks with her tail as the man is freed, she then pushes him up to the surface and noses him to the riverbank, where he is yanked up onto dry land and given CPR by Arnold Schwarzenegger.

The next day after school, the Animorphs are at the mall food court where Rachel has many newspapers reporting what happened last night. Cassie wonders what will happen to George Edelman, the man who jumped from the building, but Rachel doesn't really care, she's not responsible for him. Three days later, Rachel is in her still not completely-fixed house arguing with her sister, Jordan, about throwing out leftover Chinese food, when their mom, Naomi comes home. She tells them about how she is representing George Edelman in a case, his family wants him permanently institutionalized, not just for jumping off a building, but because the man claims that he has an alien called a "Yeerk" living in his head.

The Animorphs later gather at the mental institution where Edelman is being kept. They plan to break in, find Edelman, and see what he knows about the Yeerks. This is easier said than done because there are no open windows and it would be too far away to travel as flies or cockroaches. Luckily, a truck drives up around the far side of the facility. Tobias flies off to check what kind of truck it is and he reports that it's a food truck, so the Animorphs plan to have three of them fly into the truck in bird morph and then go into cockroach morph and hide in the food and be carried in. Jake, Rachel, and Marco are chosen, they hide behind a dumpster and morph into seagullls. They wait until the coast is clear, and they fly in and demorph in the crowded truck. They then morph into cockroaches and take cover inside a box. They find out they're inside a crate of bananas, and it turns out that a tarantula is inside with them.

They run, but the tarantula is faster, and is now after Rachel. She leaps and tries to fly, but she only gets about two inches off the ground. Rachel tries to run, but the spider rears up and jams one of its legs down on her so fast, she didn't see it move. She tries to fight and twist her way out, but there is no escape and its fangs were now descending onto Rachel. Suddenly, the cook discovers the tarantula and panics, knocking over the boxes from his dolly and the crate smashes down onto the floor just inside the lobby. One person tries to stomp them and squishes a banana and gushes out goo all over the spider and Rachel, but the spider is still clinging to Rachel's roach leg. Just then Tobias spots Rachel, and plummets down and snatches the spider away and eats it. After the spider threat is over, Jake tells everyone to move to the inside of the building, though Rachel moves a little slower because she lost a leg after Tobias rescued her from the spider. Jake, Marco, and Rachel resume moving along the wall's baseboard and enter the kitchen, where they find and enter an opening in the wall. Meanwhile, Cassie reports that she and Ax are in their raptor morphs and have found George Edelman on the second floor above the kitchen. Jake, Marco, and Rachel continue moving inside the wall until they spot an opening which brings them inside the bathroom in the room next to George Edelman's.

Rachel demorphs and asks the man in the room she is in to bring her George Edelman. When George Edelman arrives, she says she is helping his lawyer with his court case and needs to ask him some questions.

He explains that during the Kandrona starvation that occurred after the Animorphs destroyed the Kandrona, the Yeerks discovered by accident that by eating maple and ginger flavored instant oatmeal, a Yeerk could survive without Kandrona rays for longer than the maximum of three days. However, the oatmeal proved to be terribly addictive to Yeerks and drives them insane. The oatmeal replaces some of a Yeerk's brain stem and once exposed, Yeerks cannot resist becoming addicted. Edelman also explains that there is no way to get the Yeerk out of his head, it will live inside him forever.

When the Animorphs gather back at Cassie's barn, Marco points out that they now have the ultimate weapon against the Yeerks. Tobias counters that something about using the oatmeal doesn't feel right to him. Ax is conflicted, because this drug means Yeerks can live in their human hosts indefinitely, and asks, "How far into savagery do you go to defeat the savage?". Cassie doesn't know what she thinks, and Rachel recalls an earlier incident with Visser Three's twin brother, who found a way around Kandrona starvation by cannibalizing fellow Yeerks, where Cassie had demanded the Yeerk's destruction. Ultimately, the Animorphs decide they need to go back to the Yeerk pool.

Later on another day, the Animorphs gather in fly morph at the local McDonald's, which Tobias has informed them is the location of an entrance to the Yeerk pool that he has discovered by following known Controllers. Tobias says that the way Controllers get into the Yeerk pool is they go up to the McDonald's counter and ask for a "Happy Meal with extra happy", then go through a door to a walk-in refrigerator which is the entrance. When the Animorphs in fly morph follow a Controller into the walk-in refrigerator, they do not get far before an alarm sounds and a voice says "Unauthorized life-form detected". Ax explains that they need to leave immediately, because the Gleet Bio-Filter destroys all life forms whose DNA is not entered into the computer controls. The Animorphs are forced to abandon their attempt at entering the Yeerk pool through McDonalds, and must find another way to enter.

The Animorphs gather at Cassie's barn and decide to acquire moles in order to dig their way to the Yeerk pool. They take turns digging for one-hour shifts. They continue digging after school for several more days until finally Cassie in mole morphs feels that they have reached solid rock. Rachel goes down to the end and after looking around for a while, discovered a pocket of air from a seam between rocks. The next day, on Saturday, the Animorphs return and all six go down to the air entrance Rachel discovered the day before. When they reach it, Rachel falls into some kind of cave that they discover houses hundreds of bats and a lot of bat guano.

Animorphs underground book 17 inside cover bat

Rachel in bat morph

They decide to morph bats and Rachel gives a bat to Tobias to acquire, since he is the only one who doesn't have a bat morph. When they are morphed as bats, they follow their senses to where open air and thus the cave opening, must be. Eventually, they make it to the Yeerk pool and plan to dump instant maple and ginger oatmeal into the Yeerk pool. Just then, a Dracon beam from a Hunter Robot starts firing. It sears Rachel's wing off and she falls straight into the Yeerk pool. Rachel drifts until she is under the pier where humans are reinfested with Yeerks and cry out in distress to bored Hork-Bajir controllers.

There, she demorphs to human and remorphs to ant. She runs across the pier until she grabs onto the fabric of someone's shirt. She stays on the person for a while, then jumps off and runs to what turns out to be a storeroom, where she demorphs to human. She finds a dracon beam and stuns a Hork-Bajir who just then enters the store room. She also stuns a human woman, then proceeds to take her clothing and glasses as a disguise. She walks around the Yeerk Pool, assumed by other to just be another human-Controller. She finds Ax, demorphed as Andalite, trapped by thirty Hork-Bajir warriors who slide a sheath over his tail blade. She follows the Hork-Bajir Controllers who are dragging Ax to another location when she hears Marco though-speak to her, telling her that Jake, Ax, and Tobias have been taken prisoner, but she is unable to respond because she is human.

A bit later, an alarm sounds and Hork-Bajir begin running toward the storeroom where Rachel had Draconed the woman and the Hork-Bajir. After a close call with another Controller who was about to figure out who she was, she runs into Cassie. Just then, a dome opens up in the ceiling and Visser Three arrives. Rachel and Cassie decide to duck into the cafeteria, where they discover Marco in gorilla morph. Rachel and Cassie fill Marco in on Visser Three's arrival and the location of the oatmeal and begin to morph battle morphs. Rachel tells Marco to take her Dracon beam. Rachel, in elephant morph, wraps her trunk around a barrel of oatmeal and throws it into the Yeerk pool. Marco points the Dracon beam at the barrel. She exchanges words with the Visser, threatening that Marco will fire. Rachel can see in his eyes the Visser writing off his fellow Yeerks, so she picks him up and throws him into the pool. She knows that Andalites absorb food through their hooves, so the Visser would be absorbing the oatmeal through his hooves if the barrel of oatmeal explodes. Rachel throws more barrels into the pool while Cassie goes to free the others. They walk backwards up the steps of the Yeerk pool, with Marco pointing the Dracon beam the whole time.

Then, the Visser starts morphing. Seeing this, they decide their only way out is if Marco shoots. Marco does so, with the help of Tobias's hawk eyes. Rachel, weakening, falls over in elephant morph so must demorph. Jake is still in bat morph, so he demorphs as well. The Visser is morphing what looks like some kind of pterodactyl, and seems to be flying toward them. With Hork-Bajir above them on the stairs, they are trapped. So, Rachel sets the Dracon beam at maximum power, yells "mole!" and aims straight up at the ceiling and fires. The ceiling comes crashing down and they are buried alive. They all morph to mole, and slowly dig their way out of the rubble. Eventually, they make it back to the bat cave. They morph bat and follow the rest of the bats as they leave the cave toward the exit at sundown.

When Rachel arrives home, her mother demands to know where she has been. Just then, the phone rings and Naomi tells her and Jordan that her client, Mr. Edelman had escaped the institution where he was being held. Naomi continues saying that they are telling her that a grizzly bear had supposedly freed him and psychically told Edelman not to attempt suicide again. It is revealed that Rachel did this because even though she couldn't really help him, in between the mad ravings of the Yeerk, she wanted him to be free.



Supporting Characters:


Other Characters:



Major/Highlighted Events

  • The Animorphs find out that shortly after they destroyed the Kandrona in The Stranger, the Yeerks discovered that instant maple and ginger flavored oatmeal removed their ability to require Kandrona Rays permanently. However, this came with a side effect: not only would the Yeerk go insane, but they would be fused to their host's brain permanently, unable to leave and staying alive so long as their host lived.
    • The Animorphs have a moral debate on whether using psychochemical warfare against the Yeerks is ethically sound, as giving oatmeal to the Yeerks would cause them to form a drug-like addiction to it. Rachel believes that it is acceptable since the Yeerks are their enemies; Marco refuses to recognize oatmeal as a drug, while Tobias, Cassie, Ax and Jake do not wish to cross this ethical line. Tobias states that he refuses to administer drugs to the Yeerks as Cassie is torn at the realization that right and wrong isn't black or white anymore. While Jake does not want Tom to be affected by the oatmeal, he remarks that the reason slavery ended during the American Civil War was because the North fought to free all slaves rather than make a negotiation with the South to allow some slaves; similarly, they should attempt to free all Controllers rather than just some. Since hosts affected by the oatmeal would receive moments of freedom whereas non-affected hosts would never have any so long as they were infested, the Animorphs collectively decide to use oatmeal to give the Yeerks a drug addiction. Rachel privately reflects that despite Jake's decision, he personally would never subject Tom to it, wanting Tom to be completely free rather than partially free.
    • Despite agreeing, the Animorphs never end up using the oatmeal against the Yeerks and never attempt to try again in the future.
  • This book introduces Gleet Bio-Filters and Hunter Robots, two technological security devices placed in the Yeerk Pool entrances to prevent unauthorized life forms, whose DNA have not been entered in the system, access to the Pool.
  • Tobias and Rachel's relationship is touched upon again, with Rachel adding that Tobias usually flies into her bedroom every morning, and hangs out with her while she does homework. In previous books, Tobias had only visited in the evenings, and the visits were not typically every day. At the Yeerk pool, when Tobias is about to get shot via Dracon beam, Rachel shields him, causing her to lose her wings and fall into the pool. She later admonishes Tobias for worrying her to death, with Tobias replying that he was worried about her as well.


Morpher Morphs acquired Morphs used
Jake Mole Peregrine Falcon, Seagull, Cockroach, Housefly, Mole, Brown Bat
Rachel Mole Bald Eagle, Bottlenose Dolphin, Seagull, Cockroach, Housefly, Mole, Brown Bat, Black Garden Ant, African Elephant, Grizzly Bear
Tobias Mole, Brown Bat Human (himself), Housefly, Mole, Brown Bat
Cassie Mole Osprey, Housefly, Mole, Brown Bat, Wolf
Marco Mole Osprey, Seagull, Cockroach, Housefly, Mole, Brown Bat, Silverback Gorilla (Big Jim)
Ax Mole Northern Harrier, Human (Main), Housefly, Mole, Brown Bat
Visser Three -- Unnamed Winged Porcupine-like Creature


  • The cover quote is, "There's nothing to fear, but the Yeerks themselves...." which is a reference to the popular saying "There's nothing to fear, but fear itself!"
  • The inside cover quote is, "There's nothing to fear. Batgirl is here...." which is a reference to Batgirl from the Batman series.
  • This is the fifth book in which the cover art does not depict a morph acquired in the book. Rachel, along with the other Animorphs sans Tobias, acquired her bat morph in The Android.
  • This is the third book in which all the Animorphs acquire the same new morph.
  • This was the last book to be developed into a TV episode.
  • Marco mentions that Ax has been living on Earth for a few months, giving the reader a sense of time passage from the end of The Message to The Underground.
  • A new Planet Hollywood opens in their hometown in this book, with multiple Hollywood celebrities in attendance, while a previous location was featured in The Android. The presence of two active Planet Hollywood restaurants indicates that the Animorphs' city is relatively major, as a smaller city or town would not have had one, let alone two.
  • ANIBASE: This book boasts one of the longest titles in the series. Interestingly enough, Katherine Applegate didn't make up even one title for an Animorphs book -- in fact, she didn't even make up the title for the series! Instead, editors of Scholastic would receive K.A's outline for each book and would then have to rack their brains to come up with something that not only fit the book, but also sounded good when prefaced with a "The"!


  • Sara's name is misspelled as "Sarah".
  • Rachel states that Naomi is a lawyer who is not that high up in her firm; however, in The Message, Naomi received an award for "Best Lawyer of the Year".
  • Ax asks what 'willies' are, even though he already asked this question and received an answer in The Capture.
  • When Jake decides which team should go into the mental institution, he remarks that whoever goes must use a fly or a cockroach morph, and then proceeds to state that Tobias cannot go as he does not have the useful morph needed; however, Tobias acquired a fly morph in the previous book, The Warning, and even uses the fly morph later on in this book, when scouting the McDonald's.
  • There's a period omitted on p132.
  • Rachel tosses Visser Three into the Yeerk pool in order to make him absorb the oatmeal through his hooves. However, in The Andalite Chronicles, Elfangor is clearly able to shut off his hooves' ability to absorb nutrients of any kind.
  • Rachel is able to climb the stairways in the Yeerk pool in her African elephant morph. However, in The Invasion, she was unable to do so since elephants cannot climb, and thus had to partially demorph to human in order to escape the Yeerk pool.
  • A tab is missing on p160.
  • The Animorphs have a major discussion on using oatmeal against the Yeerks, spending a week digging a hole into the Yeerk pool and having Marco's father pay for multiple boxes of it. However, when they get to the Yeerk pool and find a hidden stash, they decide not to use it without explanation, only unleashing a barrel's worth in the pool as a distraction; additionally, Marco offloads the oatmeal he purchased to his friends rather than attempt to use it against the Yeerks ever again.
  • After Tobias is shot down by a Hunter Robot, Rachel swoops down to grab him, remarking that Jake and Ax have done the same and that all three were struggling to get Tobias to safety. However, on the next page, she states that Jake has just decided to swoop down from high above to help them.
  • Jake and Rachel demorph in the middle of the stairs, with Visser Three in a winged aerial morph heading toward them in one direction while a small Hork-Bajir army comes at them from the other direction. Yet, the two are never spotted. The Hork-Bajir (and avian creatures) are also said to have an excellent sense of hearing, and yet do not remark on the two human voices yelling from where the 'Andalite bandits' are.

TV Adaptation

The Underground was adapted as part of the Animorphs (TV series), which aired on Nickelodeon and YTV between the fall of 1998 and the spring of 2000. The seventeenth book in the series was covered by the seventh episode, "The Escape", which is the name of the fifteenth book in the series (the TV episode Underground bears no resemblance to its namesake book). The TV episodes did not follow the books faithfully, altering many aspects of the characters' roles within the Animorphs, the events in the war against the Yeerks, and added plot lines that were not present in the books.

  • In the episode, Marco argued for the use of morphing for frivolous purposes, while Rachel argued against. In the book series, Rachel used her morphing power the most casually, and the most often - while Marco avoided morphing at all costs most of the time.
  • In the book, the Animorphs learned about a entrance to the Yeerk pool located in the walk-in refrigerator at a McDonald's. To enter, a Controller would ask for a Happy Meal with extra Happy. They try sneaking in as flies but can't because of the Gleet Bio-Filter In the episode, because of copyright laws, it was changed so that Jake, Marco, Rachel, and Cassie are at a burger joint called Tom's Burgers in their human forms, pretending to be Controllers and they ask for a cheeseburger, hold the cheese and are sent to a storage room, and they enter, activating the Bio-Filter and alerting the Controller who worked there, but they escape in their cockroach morphs.
  • In the book, the Animorphs entered the Yeerk pool as moles and then bats. In the episode, they morphed into ferrets and Tobias somehow got in and out from underground even though he didn't regain his morphing power.


U.S. Images

International Covers

Main Series #1 The Invasion | #2 The Visitor | #3 The Encounter | #4 The Message | #5 The Predator | #6 The Capture | #7 The Stranger | #8 The Alien | #9 The Secret | #10 The Android | #11 The Forgotten | #12 The Reaction | #13 The Change | #14 The Unknown | #15 The Escape | #16 The Warning | #17 The Underground | #18 The Decision | #19 The Departure | #20 The Discovery | #21 The Threat | #22 The Solution | #23 The Pretender | #24 The Suspicion | #25 The Extreme | #26 The Attack | #27 The Exposed | #28 The Experiment | #29 The Sickness | #30 The Reunion | #31 The Conspiracy | #32 The Separation | #33 The Illusion | #34 The Prophecy | #35 The Proposal | #36 The Mutation | #37 The Weakness | #38 The Arrival | #39 The Hidden | #40 The Other | #41 The Familiar | #42 The Journey | #43 The Test | #44 The Unexpected | #45 The Revelation | #46 The Deception | #47 The Resistance | #48 The Return | #49 The Diversion | #50 The Ultimate | #51 The Absolute | #52 The Sacrifice | #53 The Answer | #54 The Beginning
Megamorphs The Andalite's Gift | In the Time of Dinosaurs | Elfangor's Secret | Back to Before
Chronicles The Andalite Chronicles | The Hork-Bajir Chronicles | VISSER | The Ellimist Chronicles
Alternamorphs The First Journey | The Next Passage
TV Tie-Ins Meet the Stars of Animorphs
Graphic Novels #1 The Invasion | #2 The Visitor | #3 The Encounter | #4 The Message | #5 The Predator | #6 The Capture