Sherman Peabody is the toy of a child named Trent, Trent's favorite toy, in fact. But when Trent leaves, all the toys come alive and start chatting with each other, and they're especially concerned because Trent's birthday party is today, and they're afraid that the new toys might overshadow them, even to the point of having them be given away. But Sherman is there to calm them down because, of course, he's Trent's favorite, or, at least, was. A new toy named Jimmy Neutron has all the latest gizmos and technology. Sherman inevitably gets jealous and tries to fight for his spot as alpha dog. Then, both Sherman and Jimmy are now lost. They must find a way to get back to Trent before he moves without them, but they will have to pass through a ruthless toy killer, Duncan Ryanson.