The time is 1925 when Steve Grendon and Sim Jones of The Moon Tenders set out from Sac Prairie for a canoe and camping trip to Prairie du Chien. They come to an old house, use the water pump, and finding the front and back doors closed, just happen to try the cellar door which is open. They trespass, Sim protesting but going along, explore the house, accidentally discover strange doings and stay around to play detective. They are caught by Charlie Ross, an Irishman with a face made to smile but a gun in his hand, who is the caretaker. The house is being used by Al Capone to smuggle liquor in from Canada; the police arrive in time; and the boys go home. Hardy Boys stuff, except these boys are dumber.