Matilda Benson approaches Perry Mason, the lawyer, to recover the IOUs that her grand daughter Sylvia Oxman had written off to clear her gambling debts with a gambling ship that cruises just beyond the twelve-mile limit. Her marriage being on the rocks, Sylvia's husband will use these against her in the divorce proceedings to get the custody of their child. The owners of the gambling ship know about this, and it only makes matters worse. Although Matilda is willing to pay a little more than the face value of the IOUs, she is afraid they might try to make both parties bid against each other in order to get the IOUs. Hence she requests Perry Mason to step in and solve the problem.
Mason goes to the gambling ship to retrieve the IOUs, and finds both Matilda and her grand daughter aboard the ship. One of the two owners of the ship is killed, and as it appears, only Mason or Sylvia could have shot him. Mason goes into hiding to escape the police so that he can solve the mystery. At the same time, one of his detective's operatives 'tells all' to the police.
Perry Mason needs to prove his own innocence, besides trusting his client and proving her innocence as well. The scenes aboard the gambling ship are very well described.
This report prepared by Ashwita