The Further Adventures of Ellery Queen - Season 1 Episode 4 The Door Between

The story deals with the mysterious death of a well-known writer which takes place while a girl believed to be the daughter of her fiancé is in the next room. Karen Leith is found dead by the girl, Eva, who is then accused of murder. Ellery Queen had met Dr. McClure—the girl's supposed father, and the fiancé of Karen—on board ship, where they learn of the killing. EIIery takes over the case when they land. A mysterious missing sister of Karen's is the possible key to the baffling death.