A series of adventures begins for the Hardy Boys after they sail their ice boat to the desolate and inhospitable Cabin Island. The boys had recently broken a car-theft ring, and one of the car owners, the elderly Mr. Jefferson, rewarded them with an offer of a stay for a few days after Christmas at his retreat on the island located near the mouth of Barmet Bay.

At the same time, Jefferson asks if the boys can help locate his missing grandson, Johnny, and a collection of valuable medals which disappeared, stolen in fact, two years ago.

Are Frank and Joe up to the challenge?