If you've seen Alfred Hitchcock's film "Strangers on a Train," you'll have a clue as to the resolution of Martha Grimes's 22nd mystery featuring British Detective Supt. Richard Jury.
This is no spoiler, since the author herself hints all through the book at the derivation of her crucial plot device. And her homage to the classic film and its director do not detract from the freshness and quality of this thoroughly engaging tale.
Ms. Grimes, a Pittsburgh native who sets her Jury novels in England, has chosen the village of Chesham, where a drab librarian named Mariah Cox is found shot to death behind a pub called "The Black Cat."
A real black cat, the pub's mascot called Morris, is observed at the crime scene at the time of the murder, but immediately disappears. A black cat is still seen in and around the pub, but the 9-year-old niece of the pub's temporary manager insists that it isn't Morris.
It turns out that the dead librarian wasn't so drab after all. She was wearing expensive designer clothes and shoes costing thousands of pounds. Mariah was spending weekends in London working for an escort service under the much sexier name of Stacy Storm.
Soon, two more young women working for escort services in London are murdered in a similar manner.
Jury, who up to this time has hardly ever noticed what shoes a woman was wearing, goes to school on fashions, aided by the wife of Thames Valley Detective Sgt. David Cummins. Though wheelchair bound as a result of a car accident, Chris Cummins has collected a roomful of expensive designer shoes that she will never be able to wear.
Further complicating Jury's life is the appearance of a young gadabout named Harry Johnson, whom Jury believes to have gotten away with a gruesome murder some years earlier.
We learn early on that Johnson has stolen Morris and replaced it with the second black cat. Johnson also happens to have a black cat of his own cleverly named Schrodinger (making three black cats in all), and a very intelligent dog named Mungo.
Morris and Mungo become friends and converse with each other, commenting on events from their very non-human points of view.
It's a bit off the wall, but this bizarre literary device allows Ms. Grimes to tell the reader things that would be awkward to convey within a normal, linear storyline. She also clutters the plot with extraneous aspects of Jury's life, among them a sad love relationship and a touching incident in which Jury saves an abused stray dog.
If you can accept all this, the mystery itself is quite a good one, Ms. Grimes's prose is lively and literate and the characters - many familiar from earlier Jury novels - are thoroughly engaging and often laugh-out-loud funny.
Robert Croan is a Post-Gazette senior editor.