Rachel continues to be reeling from the news headlines that the planet earth is secretly under strike by parasitic aliens referred to as the Yeerks. Which she and her friends — five kids who, purely by chance, stumbled onto a downed spacecraft and were given the energy to morph into any animal they touch — will be the planet’s just defense. But Rachel’s always been something of the daredevil. So if it is recommended that they infiltrate the home of their helper primary, Mr. Chapman, who also happens to be a human host from the Yeerks, she volunteers. But what she finds inside could be more than also she are designed for.