Philo Vance is hired to write a true-crime mystery... but when the facts about an unsolved crime are about to be brought out into the open a murder takes place.

Although Dale and Ken Bullock should be a happily married couple, their marriage is on the verge of a break-up, because Dale refuses to give up her well-paying job in order to devote more time to Ken and their two children Jimmy, age 9, and Tommy, age 6. They sue for divorce and the Judge rules that the children be placed in the custody of their father. Dale realizes what she has lost but she is too proud to say anything to Ken, whom she still loves. Ken, shopping for the perfect stay-at-home wife to take care of his children, falls for the charms of his secretary, Millie Lynch. Not quite.

Private Detective Philo Vance gets involved with a succession of murders and a mystery concerning the disappearance of an emerald that has been smuggled into the United States.