On their way to Monte Carlo, Monaco, Marilyn and her husband, Neil, meet several other married couples, including Julian and Phoebe, who are traveling with a lost dog they plan to return to its wealthy owner for a large reward. But, when the dog's mistress is murdered, the travelers become the prime suspects, and Inspector Bonnard is determined to track them all down.
A dog is featured and is an important part of the plot. Nothing bad happens to him, although in one scene he is in danger. Another dog appears in one scene, and though someone sits on her by accident it is unharmed.
A character is addicted to gambling. He discusses losing his business due to his gambling addiction. Later, he is seen in the casino, out of control, running around and gambling at all the tables.