When Walter leaves his pampered pet croc, Crunchzilla, to fend for itself, Dennis and the gang help him to get in touch with its wild side. Walter does his best to prevent them, as he needs to keep the croc tame in the hope of getting back his father's limo keys, which Crunchzilla has accidentally swallowed.

Dennis and the gang train Bertie in the art of standing up to people so he can rebel against Walter's bossiness - but they train him too well and he becomes a dangerous rebel without a clue!