On a rainy Glasgow night, two men go on a pub crawl. There’s nothing unusual about that, but the subject of their conversation is indeed something singular: a triple murder. One of the men, William Watt, is accused of slaughtering his wife, daughter and sister-in-law in their beds. He has a solid alibi, but the police aren’t buying it. The other man, Peter Manuel, intimates that he knows who the real killer is and that he’s willing to locate the incriminating murder weapon — or find a joe to take the rap — for cash. The catch is that Manuel himself is a hardened criminal with a trail of sex crimes and murders to his name. As the increasingly drunken men drive and stumble their way through various pubs and clubs, it becomes clear that Manuel himself is familiar with the interior of the Watt house, the site of the gruesome triple murders.

Oh, and there’s one more disquieting thing about this pub-crawl: It actually happened.

"The Long Drop," by Denise Mina (Little, Brown)

“The Long Drop” is Denise Mina’s first foray into a suspense story deeply indebted to a true crime. Celebrated for her Garnethill suspense trilogy, as well as for her Alex Morrow police procedural series, Mina has now trained her moody sensibilities on an episode from the career of Scotland’s most infamous serial killer.

Peter Manuel committed seven grisly murders (and was suspected of two more) before he was hanged on the gallows of Barlinnie prison in 1958. (That’s the “long drop” of Mina’s title.) Manuel was an exceptionally coldblooded murderer: His last set of victims was the Smart family (mother, father and their 10-year old son). After Manuel shot them on New Year’s Day 1958, he lived in their house for a week, even feeding the family cat. But, Mina’s novel focuses on the Watt family triple-murder case because it’s the one that still raises vexing questions — the kind of questions a psychologically inquisitive novelist like Mina feasts on.

Here are the facts: On the night of Sept. 17, 1956, Marion Watt, her 16-year-old daughter, Vivienne, and her sister, Margaret Brown, were shot to death in their beds inside the family’s suburban villa. The police suspected the patriarch of the family: William Watt. A prosperous businessman, Watt was unfaithful to Marion; furthermore, his alibi (an overnight fly-fishing trip on which he conveniently brought along the family watchdog) seemed too neat. When two witnesses — a ferryman and a motorist — came forward to testify that they had seen Watt in his car in the dead of night, he was formally charged. Out on bail, Watt offered a reward to anyone who could provide information about the real killer.

Enter Peter Manuel, a convicted sex offender and all-around bad seed who (unbeknownst to the authorities) had already murdered one young woman. Watt and Manuel met on the night of Dec. 2, 1957, and talked for 11 hours. Of course, no tape of that conversation exists, which leaves Mina plenty of room for speculation. Was Watt looking for his family’s murderer or in the market for a fall guy? Was Manuel toying with Watt or did he bond over whiskeys with a fellow monster? And what malevolent forces would impel Manuel or (perhaps) Watt or anyone to commit such gruesome crimes?

It’s hard to top that macabre pub-crawl around Glasgow for drama, but Mina has plenty of other provocative historical material here to flesh out — including the transcripts of Manuel’s murder trial that took place the following year. During that trial, Manuel dismissed his own attorney, took up his own defense, and — get this! — called William Watt to the stand to testify about their boozy night together.

The author Denise Mina. (Courtesy of Little, Brown)

In “The Long Drop,” Mina wants to take her readers on another sort of night journey, deep into the dark and disordered mind of a psychopath (or two), as well as into the shadow lands where the grieving families of the murder victims find themselves exiled. Here, for instance, is a passage where Mina’s omniscient narrator enters into the mind of the father of another one of Manuel’s victims — a 17-year-old girl named Isabelle Cooke who never returned from a school dance. After his testimony at Manuel’s murder trial, Isabelle’s father feels cheapened by the easy empathy of some onlookers in the courtroom:

“Angry, he looks up and catches the eye of a woman. . . . She is weeping openly, tears coursing down her cheeks, her hands clutched together as if she is holding his dead daughter’s cold feet to warm them. . . .

“Mr. Cooke thinks of the weeping woman in the gallery. His unique desolation was all he had left of his Isabelle. Now the crying woman has taken that as well. He has been robbed again.”

Even Glasgow, Mina’s signature setting, seems darker, more opaque in this novel. No doubt it’s all the soot, which is both a literal fact of life in the Glasgow of the late 1950s and a metaphor for the morally compromised atmosphere that blankets the area:

“Above the roofs every chimney belches black smoke. Rain drags smut down over the city like a mourning mantilla. Soon a Clean Air Act will outlaw coal-burning in town. Five square miles of the Victorian city will be ruled unfit for human habitation and torn down, redeveloped in concrete and glass and steel. . . . Later, the black, bedraggled survivors of this architectural cull will be sandblasted, their hard skin scoured off to reveal glittering yellow and burgundy sandstone. The exposed stone is porous though, it sucks in rain and splits when it freezes in the winter.”

As that description indicates, the narrator of “The Long Drop” sees far beyond the daily grime and grisly events of the late 1950s and, yet, mostly keeps mum, leaving readers to stumble with detectives through the fug of half-truths and lies that enshroud the story of Peter Manuel and his patsy or prey or possible partner in crime, William Watt. “The Long Drop” takes readers on a suspenseful tour into the past, through psyches and situations far grimmer than even those sooty Glasgow streets.

Maureen Corrigan, book critic for the NPR program “Fresh Air,” teaches literature at Georgetown University.

the long drop

By Denise Mina

Little, Brown. 235 pp. $26