The Mystery of the Chinese Junk — Franklin W. Dixon

Little did Frank and Joe Hardy realize when they become owners of the Chinese junk Hai Hau with Chet Morton and the rest of their friends that they are also buying into a Chinese puzzle -- and a dangerous one at that. The boys plan to use their newly purchased junk as a summertime ferry that will pay off in both profit and pleasure. But suddenly Frank and Joe are caught up in a desperate struggle between two unknown, ruthless gangs. They are threatened not to sell the boat, yet just as surely warned that they must.

What is the secret of the junk, and what does the curious, cryptic message -- “Don't sell the Hai Hau, or the curse it carries will descend on you!” -- mean?

A clue, discovered in the narrow, winding streets of New York's Chinatown leads Frank and Joe deeper into the tangled mystery that surrounds them.

The solution to the puzzle continues to elude the boys until Chet guides Frank and Joe deep into a cliffside cavern on a spelunking expedition. There, with one astounding and dynamic discovery, the Hardy Boys unravel The Mystery of the Chinese Junk