Max's little sister, Sadie, is cute, cuddly - and a real nuisance! Smash! There goes his snow den. Splash! That's the end of his nice quiet swim. Max wishes she'd just go somewhere else, so that things can go back to the way they used to be - just him and Mum. But when he and Sadie are caught in a snowstorm, Max proves what a brilliant big brother he can be.