The Casino Murder Case
S. S. Van Dine
 Philo Vance receives an anonymous letter alerting him to the possibility that violence will soon be done within a well-known family, and the letter also suggests that something of interest will take place that night at the casino. Vance attends and witnesses the collapse of the son and heir to the family fortune, a heavy gambler, due to his having been poisoned—immediately after he drinks a glass of water from the casino manager's private decanter. At approximately the same time, across town, the son's wife, a former Broadway musical star, dies from poison. The curious factor is that the medical examiner cannot identify the way in which the poison was administered to the wife, except to say that no traces were found in the stomach (and no marks of a hypodermic are found). Vance attends the son's home and investigates the wife's death—later that evening, the sister of the son and heir is also poisoned. When he recovers, the son suggests that his mother may have been responsible for the poisoning, but Vance also finds a note that suggests that the wife committed suicide. There are other characters connected with the family upon whom suspicion falls, including the sister's two suitors, one of whom is the family physician and the other the chief croupier at the family casino, and the children's uncle, who manages the casino. Vance must determine the method by which the poison was administered and at the same time follows a trail that leads to one of the character's research into the production of deuterium, or "heavy water", which had just been discovered in 1934. Having worked out the murderer's plot and identity, Vance puts himself at the mercy of the murderer, who is holding Vance at gunpoint, in order to hear a confession—then the murderer is killed in an exciting climax.