John Dickson Carr is best known as the master of the locked room mystery, a subgenre I particularly enjoy...enjoy being mystified by that is, since I never manage to solve them. Surprisingly, considering his frequent use of English settings and detectives, Carr was born in my home state, Pennsylvania.

The Unicorn Murders, written under the name Carter Dickson, featuring as detective Sir Henry Merrivale, is not a locked room mystery but rather a similar "impossible crime." How is a man killed, in full view of several witnesses, his inexplicable wound seemingly inflicted by an invisible unicorn?

In an old Chateau cut off from the outside by flooding, Carr asembles four detectives, including a French sleuth, along with a notorious criminal mastermind, and assorted suspects, any of whom might be either the French sleuth or the villain since both are masters of disguise. You might think this set up would require quite a bit of improbable contrivance to achieve, and you'd be correct. This 1935 novel is not for readers who demand realism. But then, one of the reasons we have fiction is to imagine things that would never happen in real life.

Aside from being a brilliant puzzle-maker, Carr is also wonderful at creating atmosphere and the book drips with it, almost literally since much occurs in a driving rain. The chateau is suitably eerie, and the crime decidedly creepy. Although it is made plain that a human killer is at work, the whole tale is nevertheless tinged with an aura of supernatural dread. You know there's a rational explanation, but it's hard to think of one.

The solution is perhaps a bit too complicated to qualify as classic but it does make sense and nothing too esoteric is dragged in to make things work. If, like me, you enjoy contemplating, or attempting to explain, seemingly impossible events and then reading in amazement (well, I'm always amazed) as the solution is revealed, you'll probably like The Unicorn Murders.

Coincidentally, Martin Edwards just recently reviewed another John Dickson Carr novel, Hag's Nook on his blog, Do You Write Under Your Own Name?.