On a sleety December night taxi-driver Spike Walters picks up a fare at Union Station. The well-dressed, veiled woman instructs Walters to drive to a poorer part of town but when he arrives at the address given she has vanished from his cab, leaving her suitcase -- and a man's body. Of the missing woman Spike asks himself, as will the reader, "Where was she? How had she managed to leave the taxicab? When had the man, who now lay sprawled in the cab, entered it?"
Chief of Police Eric Leverage and amateur criminologist David Carroll cooperate in solving the crime. The departed is identified as club man Roland Warren, a cad rumoured to have been involved with a number of socially prominent married women although there has been no open scandal, and just as well being as he is engaged. It transpires every article in the suitcase belonged to him and this, along with certain other evidence, convinces the authorities and the public that Warren was planning to elope -- but not with his fiancee. Given the dead man's reputation of not being too fussy about whose wife he romances, a number of upper crust persons naturally come under suspicion, and then there's Warren's just discharged valet, not to mention the bereaved fiancee.
My verdict: Midnight features a fairly complex plot unreeled at a slower pace than in many works. Older novels of detection often display social mores that seem strange to modern eyes, for example not mentioning a woman's name at the club or the terrible consequences of cheating at cards or in some other way being touched by the rancid breath of scandal. David Carroll must navigate these treacherous waters to solve the mystery of the who and how and why of the crime.