Who or what is taking the kitchen scraps from the garbage every night? What starts out as a puzzle becomes a mystery. Every night Grandma leaves table scraps in a wrapped plastic bag in the garbage can where, according to plan, the McNellis children pick them up to feed their kittens. But the plan changes when the bag is gone in the morning. The twins, Liza and Bill, and brother Jed decide to investigate the matter.

First the children discover Liza's missing red sweater in a part of the woods she hadn't been to before, next they read about runaway children in the newspaper, and then their new puppy is lost. Finally they find a teepee in the woods with what seems to be Indians in warpaint dancing and shooting arrows! The young detectives must put all the clues together and solve the mystery.