Papa La-Bas by John Dickson Carr (1968)
It's 1958 and Richard Macrae, Her Brittanic Majesty's Consul in New Orleans, has been in the city for a year. The duties are light and he has been fortunate to make some good friends and acquaintances, but for the past seven weeks he has had a strange feeling that he was being followed and spied upon. He is also in love with a mystery woman he has seen only once.
Expecting a new consular assistant from England, he is surprised by a visitor instead -- Isobel de Sancerre, the wife of his friend Jules de Sancerre. Madame de Sancerre is concerned about her daughter Margot, who has been acting strangely and asking questions about Delphine LaLaurie, who was said to have a penchant for torturing her slaves, and about Marie Laveau, the Voodoo Queen of New Orleans. Interestingly, Margot's unusual behavior began about the same time that Macrae began feeling he was being watched.
Harry Ludlow, the young consular assistant, arrives and Macrae's close friend Tom Clayton decided Harry should be introduced to the city's many pleasures by first attending a quadroon ball -- where many of the city's most beautiful and available quadroons appear wearing masks. (Clayton, by the way, has been seeing Margot.) Macrae joins the two and, on arriving sees a carriage pull up containigng his mystery woman another beautiful woman. Macrae lingers outside the ball while his friends and the other woman go in. He learns his mystery woman's name -- Ursula Ede -- and after some repartee, Macrae finds himself still smitten with the woman, and she appears to be smitten with him.
The woman who accompanied Ursula was Margot de Sacerre, Clayton's sweetheart and the one who had been acting oddly. Soon there was a rucus from the hall, and Margot ran out, fleeing, and got into her carriage, ordering the her driver to go away fast. Margot is followed from the hall by the notorious gambler Square Nat Rumbold and Tom Clayton. Rumbold, seeing Margot masked, assumed she was an quadroon and made improper advances.
Ursula and Macrae race after Margot's carriage, keeping a watchful eye on both doors to her carriage.
When her carriage pulls up to the de Sancerre mansion, it is empty! The locked room mystery for the author is justly known is a runaway carriage mystery in which a woman vanishes while the carriage was under constant surveillance.
Macrae and Ludlow join friends at the de Sancerre mansion in an effort to solve this mystery. One of them, a respected jurist falls down a flight of stairs and is killed. Accident or murder? Five friends were witness to the fall and could swear there was nobody at the top of the stairs with the judge. Another friend arrives, Senator Judah P. Benjamin. Despite the impossible circumstances, Benjamin is convinced that the judge was murdered. Benjamin insists that they call police sergeant Tim O'Shea, the most capable man on the New Orleans police force, to the scene. O'Shea, however, was on the way, having earlier received a card warning him of Margot's disappearance. The card bore the mysterious signature of Papa La-Bas, another name for the devil.
An impossible disappearance. An impossible murder. Mysterious messages from Papa La-Bas. An unknown spy, Unexplanable behavior. A link to the long-dead Delphine LaLaurie and to the feared Voodoo Queen Marie Laveau. John Dickson Carr mixes them well with a knowledgable detail of New Orleans history and customs.
Papa La-Bas is a later novel from John Dickson Carr, the second or third published after the author suffered a stroke that paralyzed his left side. He would publish only three more novels before his death. To my mind, Carr's later novels fade in comparison to earlier books. The spark is somewhat less bright. The macabre elements less eerie. The puzzles less complex. But even minor Carr is worth-while, and so is Papa La-Bas.