A whole lot of plotting going on in John Connolly’s The Unquiet

The Unquiet by John Connolly. Hodder & Stoughton, 474pp, £14.99.

“Are you a hollow man, Mr Parker?” That’sonly one of several heavy questions that Charles “Bird” Parker must puzzle over as he gets involved in another seemingly routine job - but fans of John Connolly’s thrillers know there’s never anything routine about the caseload of the morose Portland, Maine PI, who has a penchant for sniffing out paranormal horrors in seemingly mundane crimes.

The case in question in The Unquiet, Connolly’s sixth Parker novel, concerns a controversial psychiatrist who disappeared years previously after allegations arose about children being abused while in his care. he doctor’s grown daughter has taken action to have him legally declared dead. But suddenly she is being harassed by Merrick, a contract killer, hardened jailbird and self-styled ”revenger” who apparently believes the disgraced doctor is still alive - and has his own burningly personal reasons for finding him.

The daughter hires Parker for protection from Merrick and, if it comes down to it, to “persuade” the revenger that bothering her is pointless because she doesn’t know anything about her father’s fate. Even as Parker is haunted by his own personal demons - the spirits of his murdered wife and first daughter continue to hover about the old house, and his relationship with the mother of his second child has gone disastrously south - something about his client and the case nags at him, a gnawing realisation that, yet again, he’s knocking heads against malevolent forces, not all of them of this world.

Backed up, as ever, by his trusted best friends Louis, the gay black assassin, and Louis’s nimble-fingered lover Angel, Parker takes the investigation to a long-abandoned religious commune in northern Maine, to a barely glimpsed army of wraith-like shadows, to two paedophile rings, one involving the Russian mafia and the other a secret group of bird mask- wearing perverts, to an old adversary from a previous crazy case, to . . . well, suffice to say there’s a whole lot of plot going on in The Unquiet.

Regular Parker readers should perhaps be alerted to the fact that this sombre novel is a different beast from the last instalment, the entertainingly overblown The Black Angel. The body count is only in single digits, and Connolly continues to hold off on the explicit grisliness of his early books. True, abused children are once again the object of concern, but the details are more grimly realistic and less exploitatively Grand Guignol than, say, those in Dark Hollow. For nearly 300 pages, in fact, The Unquiet feels just a teeny bit anonymous - not bad, but not all that different from a hundred other above the average cop/private eye thrillers.

But Connolly knows where he’s going with the story and the mood he wants to set, and in the last third of he ratchets up the stakes. He elicits empathy for Merrick, by any measure a bad, bad guy, and, in two fascinating confrontational scenes between Parker and He/It-who-will-not-be-named here, writes superbly mesmerising dialogue. You’ll be running shards of it through your mind after the book is finished. (Advice: for maximum impact, first read The Reflecting Eye, a Parker novella in the Nocturnes collection.)

The Unquiet, which is Connolly’s ninth book in as many years, follows the genuinely strange The Book of Lost Things. Both novels, as well as Nocturnes, demonstrate that the author is now just as interested in developing iconic themes and an intense atmosphere of unease as in creating more serial killers for Parker to blow away. The Unquiet ends with the tantalising suggestion that the detective, after years of relentless, self-righteous violence, has literally lost his soul - and that the ultimate enemy has yet to come. I can’t wait.