Andy has an sleepover with Steve Mills, his best friend, and they go trick or treating in costume, accompanied by Snowy, in costume as the "The hound of the Baskervilles."
A little girl gets lost, and the two little boys, with the big dog, try to find her.
A sudden emergency requires decisive action. Andy is in an icy mountain river, above a waterfall, holding onto a branch with one hand and the girl with the other. He is not strong enough to climb onto the tree, unless he releases the girl.