- Philo Vance, dilettante detective
- John F. X. Markham, District Attorney
- Margaret Odell, Broadway beauty, found murdered in her aparrtment
- Amy Gibson, Margaret Odell's maid
- William Jessup, telephone switchboard operator
- Charles Cleaver, a man-about-town
- Kenneth Spotswoode, a manufacturer and Margaret's date that evening
- Louis Mannix, a fur importer
- Dr. Ambrose Lindquist, neurologist who is quite cozy with Margaret
- Tony Skeel, professional burglar
Locale: New York City
Synopsis: Margaret Odell, known as "The Canary", is murdered in her apartment, and found the following morning by her maid Amy Gibson. Witnesses and evidence show no one entered or left the apartment at the time, and it appears the assailant had been hiding in a closet waiting for her to return home from a date.
Interior of apartment
It seems like a classic locked-room mystery, although quite obvious someone was hiding in the closet since the keys were found on the inside of the closet door! The only door to the apartment was under constant view by the telephone operator.
Floor plan of first floor
Skeel is the only one known to be in the apartment at the time. But while narrowing down the possibilities, Skeel himself winds up murdered.
Vance finds the culprit by staging a poker game and applying the psychology of poker to the players.