This article is written from a Real World point of view.
"One wrong move and Tobias was gone. Ax might be demorphing in front of people who might be Controllers. Rachel... no one knew whether Rachel was even conscious and capable of demorphing. Or alive at all. And now the three of us were utterly vulnerable, weak, pathetic. I just kept thinking: This wasn't even supposed to be a very dangerous mission. And now, we were as close to being wiped out as we'd ever been."

The Warning, published in February 1998 and written by K.A. Applegate, is the sixteenth book in the Animorphs series. It is the fifth book narrated by Jake, and the fourth book with Jake as the sole narrator.


Official Description

Jake's made a pretty amazing discovery. It seems like there may be other people who know about the invasion. Others who know about the Yeerks. Jake finds a Web site devoted to the Yeerks. And Jake, the other Animorphs, and Ax aren't sure it's too good to be true.

But if they try to investigate the site and it's a trap, there's no way the Yeerks won't find out who they are. If they don't check it out, they'll never know if they're the only ones fighting. Whatever Jake and the others decide to do, they've got to move quickly, because Visser Three isn't the only one dying to meet them...

Plot Summary

This section needs a rewrite
Jake is on his computer, where he types into a search engine "Yeerk". Expecting nothing, Jake is amazed to see that there was one match to the word. He later gathers the other Animorphs at Marco's house because Jake needed a computer and Marco's computer was better than his. He shows them the web page, which is entirely devoted to letting the world know about the Yeerks. Jake clicks on the "Types of Yeerks" page, which shows drawing of different aliens, one of which looks just like a Hork-Bajir. Marco, Cassie, and Rachel think that the page is either a mix of truth and lies, or just a coincidence. Jake then clicks onto a list of known Controllers and points to the name "Chapman". He wonders why whoever put the site together doesn't mention The Sharing, which means either they don't know about The Sharing or this is a Yeerk trap.

Cassie decides that they should check out the chat room, but Jake's not sure it's safe, Marco offers to hack the system, but Ax offers to encode Marco's software in a way that will make it impossible for anyone to trace them. Marco reluctantly agrees and Ax sits down and types in a code making Marco's computer hack-proof in just three minutes. In the chat room, the Animorphs watch a conversation that's going on, one person that goes by username "Chazz" talks about how serious the Yeerk threat is, while username "Gump8293" is worried because his dad maybe a Controller. The Animorphs believe this could be a Yeerk scam, but Cassie isn't so sure. She thinks there's something real about the people in the chatroom, especially Gump. Jake also has the same feeling, but Ax couldn't tell, and Marco thinks it's a little of both: the web page was created by Yeerks to help them locate any humans who knows about them, while at the same time, it got a little out of the control. Jake then asks Ax to hack in and penetrate the protected screen name files, but after a few minutes of typing furiously, he is unable to get into Web Access America's central computer. Marco then comes up with an idea: they travel to WAA's main office, sneak in and get the real names behind the screen names from the main computers.

The Animorphs gather at the airport on a Saturday morning. Because it would be too far away for them to travel to and back from WAA's main office. Their plan is to morph into houseflies and sneak on board the plane. At Web Access America, Marco and Ax hack into the WAA records and discover the identities of some of the screen names on the Yeerk website. They need a distraction, so the children morph and create a spectacle for anyone working in the offices. One of the users from the website is the founder of WAA himself, Joe Bob Fenestre – the second richest man in the country.

Animorphs warning book 16 inside cover

Jake in rhinoceros morph (inside cover)

Back home, Jake needs to form a new plan to infiltrate Joe Bob Fenestre's multi-million dollar compound. Cassie objects, instead wanting to save a young child on the Yeerk website going by the screen name of Gump from confessing to his Controller father what he knows. Jake and the others overrule Cassie, deciding that Fenestre is the more pressing matter. Jake, without any prior intelligence or preparation, sends himself and the Animorphs to the billionaire's property. They are immediately attacked by gun-toting humans and pack hounds, and Rachel is shocked unconscious by a bug zapper. Ax is captured by the dogs. Jake and the others, shaken, need to find another way to break in. Jake travels to The Gardens zoo complex, and acquires a rhinoceros morph. He morphs and breaks through the entrance to the Fenestre mansion, impervious to human shotguns. The others follow, and morph their standard battle morphs.

They find Fenestre, along with Rachel and Ax in a suspended time state known as "biostasis". The Yeerk controlling Fenestre explains to Jake, Cassie, Marco and Tobias that he is Visser Three's twin brother – Esplin 9466 Lesser. Visser Three, unwilling to share his power with his sibling, banished him to Earth as a lowly telephone operator. Esplin, combining his Yeerk technical knowledge with his host's human knowledge, created a web service that would serve as a vast pool of information for the Yeerk invasion. The Visser was enraged, and has been plotting to kill him.

Jake asks Esplin how he survived without a Yeerk pool. Esplin unemotionally explains that he finds human-Controllers on the Yeerk forum. Every three days he has them kidnapped, splits the hosts' heads open, and feeds on the Yeerk inside. Fenestre admits that he is a cannibal serial killer. A horrified Cassie tries to attack him, but Jake stops her. He'd rather allow Esplin to kill as many Yeerks as he could – even it means sacrificing the host. Cassie is enraged. Jake threatens Esplin, and they leave with Rachel and Ax.

The next day at school, Jake looks for Cassie, but he doesn't see her and realizes that she wasn't in school and Jake knew exactly where she was. He makes his way to the school roof and flies off in his falcon morph, and searches around for the nearest elementary school, where he spots Cassie in wolf morph speaking to a young boy. The boy pets Cassie and walks back to his classmates, and Cassie jumps the fence and fades towards some nearby trees.

She explains to Jake that she pretended to be a magic, talking wolf to Gump, and told him not to go onto the chat room again, to not talk about Yeerks to his father, and to never trust his father. Cassie then cries over doing such a terrible thing, but Jake explains to her that it was the best she could and that it is difficult to fight evil without doing some along the way. She walks away and Jake doesn't stop her. A few days later, the news reports a fire at Fenestre's mansion, with Jake remarking that Fenestre's protection from the Animorphs no longer exists. The question of who committed the arson is left open to interpretation, although it is heavily implied that one or more members of the Animorphs were responsible.


Featured Characters:


Other Characters:



Major/Highlighted Events

  • Visser Three's Yeerk name is revealed to be Esplin 9466 Prime.
  • It is revealed that Visser Three (Esplin 9466 Prime) has a younger, twin brother known as Esplin 9466 Lesser, who used Yeerk technology to create Web Access America and make his host, Joe Bob Fenestre, the second wealthiest man in the country. After Visser Three had exiled 9466 Lesser to starve from Kandrona starvation, the Yeerk used the WAA chat rooms to find known Controllers, kill their human host and then grind the Yeerk into an edible food for sustenance.
  • Cassie, a pacifist by nature, attempts to kill Joe Bob Fenestre and his Yeerk as revenge for killing human hosts for food, and even goes as far as asking Jake to do it for her.
  • The Animorphs discuss the morality of acquiring and morphing humans for the first time, with Marco, Rachel and Ax supporting it; Jake remains semi-neutral while Cassie is opposed to it, believing that it should not be done without a human's consent.
  • Rachel and Marco's relationship is touched upon for the first time, with Jake wondering whether the two tease one another because they secretly like each other, or whether they really dislike one another. The book is filled with various insults or remarks said between the two, with Marco and Rachel both complimenting the other if they delivered a good comeback.
  • Jake offers to leave Fenestre and his Yeerk untouched so long as he stays inside the mansion, despite Cassie's desire to end his life. A few days later, the mansion is set on fire and Jake remarks that the protection no longer exists, although Jake omits to specify who was responsible for the arson. It is implied that the Animorphs, or at least Jake, Cassie and most likely Rachel, committed the crime.


Morpher Morphs acquired Morphs used
Jake Rhinoceros Housefly, Siberian Tiger, Peregrine Falcon, Rhinoceros
Rachel -- Housefly, Grizzly Bear, Bald Eagle
Tobias Housefly Human (himself), Housefly
Cassie -- Housefly, Skunk, Osprey, Wolf
Marco -- Housefly, Osprey, Silverback Gorilla (Big Jim)
Ax -- Human (Main), Housefly, Northern Harrier


Animorphs warning book 16 flipbook

Jake morphing Rhino flipbook, from the pages of the book.

  • The cover quote is, "Now it'll take more than the truth to set you free...."
  • The inside cover quote is, "Sometime you have to blow your horn...."
  • This marks the first time that Jake communicates via thought-speak with a Yeerk/Controller, in this instance being Esplin 9466 Lesser. He is the fifth Animorph to do so, after Ax, Marco, Cassie and Rachel.
  • This book also marks the third instance where the Animorphs are on a mission on Earth outside of their hometown, following their rescue of Ax in The Message and their Sario Rip adventure in the Amazon Rainforest in The Forgotten.
  • When Ax is asked to identify the green aliens that are often described in alien conspiracies and abductions, he refers to the Skrit Na, and an adventure that Elfangor once had with them. The adventure that he's talking about is actually a part of Elfangor's journey from The Andalite Chronicles.
  • ANIBASE : Cassie is the only dissenting voice amongst the Animorphs regarding the Internet in this book – and it turns out that she feels the same way Katherine Applegate does! Here's what K.A. had to say about the Internet:
    • "I'm afraid I have a fairly one-sided view of the Internet. I realize I'm using it right now, but aside from this sort of experience, I find the Web a huge disappointment. If I want research, I can get what I need ten times faster in any Barnes & Noble. As for chat rooms, they tend to sink rather quickly to the level of the lowest common denominator, which, given the anonymity of the Web, is pretty low. Then again, maybe I'm just old."
  • Fans created web sites pretending to be real web sites based on the sites mentioned in this book, such as


  • Despite the series releasing one book a month, the ad for this book featured in the previous book, which was released in January 1998, states "releasing in March".
  • The inside cover features Jake in rhino morph at The Gardens and an osprey soaring in the air above; Jake did not morph into the rhinoceros until he was outside Joe Bob Fenestre's mansion, and the only one in raptor morph with him was Tobias, who does not possess an osprey form.
  • How would Jake know how to spell "Yeerk", as it is a Yeerk language word with no established English spelling.
  • How can Ax alter Marco's computer on p22 so he'd win every game? Online games don't save scores or they would have different preferences.
  • Marco's attitude changes from the previous book. In The Escape, he wants Jake to admit that they would all stay the same after the war as they were before. In The Warning, he mocks Jake for thinking that he could go back to his old way of life after the war.
  • Rachel in grizzly morph handles a mop, which requires a dexterity that bears don't have as they lack opposable thumbs.
  • When Jake, Rachel and Cassie morph in the WAA headquarters' janitor's closet (with Tobias demorphing to his red-tailed hawk form), Jake mentions that everyone has their shoes tied around their necks except for Tobias, stating that they would leave Tobias's shoes behind in the closet and would retrieve it later. However, after providing a distraction, the four head into an elevator where they demorph (with Tobias assuming his human morph). Despite not having returned to the closet, Tobias has shoes on his feet again.
  • When Jake recounts who in the chat room is out of town and is close enough for them to reach, he mentions Chazz in both categories.
  • Jake is able to acquire the rhino while he is still partially in falcon morph, having not yet demorphed entirely.
  • Esplin 9466 Lesser wouldn't have the full three days of Kandrona Rays from cannibalizing his fellow Yeerks, because the Yeerks he feeds on would not be absorbing any at the time of their consumption; additionally, the Yeerks he would target could have last replenished their own intake less than three days prior to their murder.


US images

International Covers

International Back 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