The zombie secret is out! Sort of... Scientists at the lab that Arnold escaped from claim they've changed their tune. Instead of creating super zombie soldiers, they just want humans and zombies to be friends. Too good to be true? Probably. But Arnold agrees to help teach other zombies everything he's learned so far about being a real human boy. But there's something that seems strange about these new "zombies" (well, stranger than usual). Arnold...

Bored by the lack of crime in Quietville lately, Jimmy's vampire dog, Abby, has chewed up his mother's entire shoe collection, and so his parents have insisted in enrolling Abby in obedience training, and the longer it goes on the more "normal" (and boring) she becomes--but when mysterious things start happening to Jimmy's lacrosse team, he and his friends (the Crimebiters) realize they need to get Abby back to her crime fighting ways.