Central Kansas Library System

Relates the exploits of the four Alden children as they locate a missing man. The Boxcar children travel to Maine, take canoes into the wilderness and live in a house exactly like the one on Surprise Island, except the Maine house is brown, not yellow. They then untangle the mystery of the two houses.

The Alden family rents a houseboat to drift down the river and encounters a mystery in the little towns along the river, involving a fast black car.