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!

Gnasher becomes the star of an action movie, playing Grizzly's on-screen sidekick. But filming keeps him and Dennis apart, leaving Dennis feeling lonely. Could Dennis and Gnasher really become Grizzly and Gnasher?