On The Run Jake walked into the mall's arcade and computer zone and sat down next to Marco. They started to argue about a pair of wheels and Jake won because Marco let him. A weird message popped up on all the screens. They looked worried because the Yeerks had said they had the disk that Elfangor gave them, so Jake morphed into an iguana and Marco put him in a tank. A Yeerk came and was searching for an Andalite, which he thought Jake was. Marco tried to morph into a security guard, he but couldn't so he headed back to the pet shop. Jake said that he was a parrot and told him to put the disk on top of the iguana tank, then Marco came and picked him and the disk up. When they were leaving, a security guard came and he told Marco to give back the lizard. Marco started to run and once he turned the corner, both he and Jake morphed. Jake was holding a rat in his pocket. When they had gotten out of there Marco realized that he had left the disk. When they went back there it was missing and they saw the trash guy, so they followed him. Marco dove into the Dumpster and started looking for the disk. Meanwhile, Rachel and Cassie went to the Sharing. Rachel morphed into a fly and listened to the secret meeting in the back room. When she came back she saw her cousin Tom, Jake's brother, and they left. Jake, Rachel, Marco, and Cassie met and they realized that the disk had a homing device on it. They got rid of the disk and went home.
The Escape Cassie, Jake, Rachel, and Ax were talking in a diner. They saw a man eating maple oatmeal and asking for more. The people called the police and he went berserk. The Animorphs saw him scratch his ear, which is what a controller would do, and later they find out he knew about Yeerks. They go and see the man in an insane asylum and find out about the oatmeal and how Yeerks crave maple like some humans crave cigarettes. The Animorphs sneak into a Yeerk pool by digging into it and throwing 12 balloons into it. They poisoned the Yeerk pool and all the Yeerks who were in it died. Jake said the Yeerks would live forever in their mind and never get it out of their head. Jake said that he could not live with a brother knowing there was a slug in his head, so he said he couldn't do it to him. Marco said isn't a little freedom better than none, but he still wouldn't say yes. From then on maple oatmeal was a weapon against the Yeerks.
The Reaction Cassie and Rachel were on a field trip and saw a boy jumped into a crocodile pit. Rachel and Cassie went in after him to help. Cassie acquired the crocodile's DNA while she was in the pit. She got out of the pit with the boy. Later Cassie found out that they where invited to a show and it had a guy they thought was cute in it. When Cassie and Rachel met him, he was a real pushover because he had a Yeerk in his head. When Cassie absorbed the crocodile's DNA, she became allergic to that morph. She threw up a crocodile, which scared the Yeerk out of the guy and the crocodile ate the Yeerk. Cassie said she was sorry that she was allergic to a crocodile DNA.
The Leader, Part 1 Marco was talking to his dad and they started painting the walls, and then they started painting each other. Jake was on the computer looking on the Internet when the phone rang. He went into the hallway, seeing his brother the Controller there. He went back into his room and morphed into his dog homer. He went into his brother's room and overheard that a piece of the Kandrona, a sun from the Yeerk's home world, was being kept in the EGS broadcast tower. The Animorphs met at the tower and sneaked in. Jake and Marco morphed into lizards, then an alarm sounded. A box closed around Jake and Marco and blasted off to the blade ship. Cassie and Rachel went inside and went into the vent nearby and got out of the tower. Jake and Marco get off onto the blade ship and found out that Marco's mother was alive and was actually Visser One.
The Leader, Part 2 Marco and Jake found themselves aboard the Yeerk mothership. Marco saw his mother and then the Commander announced her as Visser 1. Marco and Jake followed Marco's mother. They wandered around a bit and ran across the blade ship. Then they headed back, because Marco wanted to get his mother. Some guards started attacking them, so they ran to the blade ship and took off. Ax contacted Jake And Marco and told them to activate the autopilot, which they did. The autopilot took them to earth. Ax, Rachel, and Cassie all were glad they were home.