The victim was stabbed inside a locked and bolted room, and witnesses insisted nobody could have entered - or left - the room. Police Lt. Marshall needs help from an inquisitive nun, Sister Ursula, to uncover the truth.

Banker Franklin Shore had run away from his wife a decade ago. Now somebody claiming to be Franklin Shore was on the phone, asking a family member to help him meet with lawyer Perry Mason. Unfortunately, murder intervened.

Oswald Preston was a very unpleasant man. But was that sufficient reason to murder him on the train?

The millionaire philanthropist died on her way to the operating room - strangled while waiting for the surgery. Ellery Queen realized that in order to determine the WHO, he'd need to uncover both the WHY and the HOW.