Nine books in to his Detective Roy Grace series set in the mean streets of Brighton, and best-selling crime writer Peter James’s trade-mark investigativeness shows no signs of flagging – except, and I am sorry to say so, in what appears to be an irrelevant sub-plot about Superintendent Grace’s former wife, Sandy.

Elsewhere the Jamesian hallmarks are in full flow, as the author has fun name-checking friends and enemies alike. Guess, for example, in whose honour chief villain Amis Smallbone is named. There is also James’s obligatory nod to his mother, Cornelia James, ensuring that one of his fashion-forward women characters always wears a CJ scarf or gloves. (Mrs James, who died in 1999, was a Viennese Jewish refugee who fled to Paris in 1938 and subsequently became the Queen’s glovemaker; James has a vast Jewish family, the Katz clan.)

In this new book, James has taken his inspiration from the New York gang wars of the turn-of-the-20th-century waterfront, when Irish gangs fought Italian gangs and no mercy was accorded to anyone. Slightly stretching incredulity, he has been obliged to make one of his main protagonists 95 years old, but the character is no less enjoyable for that. The essential storyline involves the nearly century-old murder of the nonagenarian’s parents in New York, and Roy Grace’s desperate attempt to track down today’s master criminals.

Although at times it’s difficult to know who we should really be hating here, our Brighton beau gets plenty of help from his familiar cast of American cop colleagues and his own Brighton squad of irregulars; and in this book Grace is a new father and is coping with all the late nights and sleeplessness that involves, besides taking steps, finally, to have Sandy declared dead so that he can marry his partner, Chloe. Oddly, James has decided to kill off one of his back-story characters – perhaps to open up the possibilities of new romance in the next novel.

My sense is that James is slightly fed up with the Sandy plot, which he began nine books ago as a genuine mystery as to why this rather nice man’s wife had disappeared into thin air. In the last novel, we learned, rather hurriedly, that she had simply been fed up with being a cop’s wife and had somewhat improbably, decamped for Germany. In this book, she adds little or nothing to the story, which is a fine, page-turning thriller.