Carl Houser, a bookkeeper at a bank, tells his boss he is quitting. He's not unhappy with his job, he says, he just wants to spend more time with his family and take them on a vacation. Houser then goes and loads up his money belt with cash before leaving.
Next we see Perry and Della on a cruise ship that is sailing from Vancouver to Los Angeles. The two have been working on some contract in Vancouver and decided to take a leisurely voyage back. I don't understand why a Canadian client would want an American lawyer, or why that would be the least bit legal, but at least Della is getting a sea voyage out of it.
On board Perry and Della meet the Houser family, on the previously mentioned vacation. Mrs. Houser wants to meet with Perry discreetly. When alone she says that she thinks that her husband has embezzled the money they are vacationing on and that she counted the money he has in his belt and it amounts to over ninety thousand dollars. She is hoping if she agrees to give the money back that the bank won't prosecute her husband.
But Carl Houser is lost at sea during a storm before anything can be done or discovered about the mystery money. And even though Mrs. Houser claims not to have been with him on deck it is proven that she was, and besides that Perry saw her go outside with Carl. Mrs. Houser is charged with killing her husband, even though there is no body at this point. When Paul Drake investigates, he discovers that there is no money missing at the bank where Carl worked. His books balance perfectly. So where did that money come from? Watch and find out.
One of the plot devices is pretty obvious even for novice viewers, but the mystery of where the money came from is pretty well done. However, I was never satisfied that Mrs. Houser had any motive to kill her husband.