The robber disappears from the scene of the crime without a trace and when the burgled house turns out to be Hilary's, the children have the perfect excuse to investigate.

The mysterious thief leaves only a few clues behind — enormous footprints, glove prints, a strange criss-cross mark on the ground and two torn pieces of paper.

The only people in the village with feet big enough to fit the footprints are Mr Goon (the local policeman) and Colonel Cross, neither of whom seem a likely culprit.

Fatty uses his disguises to gather important information and in doing so outwits Mr Goon, especially when both go at the same time to see Colonel Cross to ask him about his large shoes.

Tired and frustrated at their lack of progress, Pip plays a practical joke on the others, wearing a pair of large boots and leaving giant footprints for the others to find and search in vain for the thief.