Strike and Robin are just as magnetic as ever in “Career of Evil,” but Ms. Rowling, alas, has plopped them into a story line that feels like a halfhearted recycling of episodes from “Law & Order: Special Victims Unit” and “CSI: Crime Scene Investigation.” The result is a lurid and predictable novel — not as disappointing as Ms. Rowling’s first post-Harry Potter venture, “The Casual Vacancy,” but only because of Robin and Strike.

Image Credit... Alessandra Montalto/The New York Times

Things get off to a fast, if overly blunt start with Robin receiving a package containing a woman’s severed leg, and a note quoting some sinister Blue Oyster Cult lyrics (“A harvest of limbs, of arms and of legs …”). The story soon snowballs into a London-wide hunt for a serial killer billed in the tabloids as “a 21st-century Jack the Ripper.” There are twisty story lines involving rape, child molestation, wife beating, prostitution and drug abuse, and there are lots of gruesome scenes featuring murder, maiming and mutilation — some written from the killer’s point of view. Some of these scenes are so contrived and sensationalistic that the reader wonders if Ms. Rowling was actually trying to send up thriller and horror genre clichés — perhaps echoing Blue Oyster Cult’s penchant for using tongue-in-cheek humor to satirize heavy-metal tropes and conventions.

Strike — who had been in the military police’s Special Investigation Branch before becoming a private investigator — quickly comes to suspect that the killer who sent Robin the leg is one of three “twisted individuals who’ve all got good reason to hate my guts.” One is Jeff Whittaker, his sadistic stepfather, who was acquitted of murdering Strike’s mother. Another is Donald Laing, “a clever, devious animal; a sociopath” who violently assaulted his wife and was sentenced to 16 years in prison based on Strike’s evidence. And the third is Noel Brockbank, a serial pedophile, who sexually assaulted his stepdaughter and who’s managed to elude justice despite Strike’s best efforts.

Each of these men could be said to have a “career of evil,” but they’re all a lot less interesting than Voldemort in “Harry Potter.” (The song “Career of Evil” was reportedly inspired by a 19th-century poem, “Les Chants de Maldoror,” about a Voldemort-like figure opposed to God and humanity.) These three suspects represent no existential challenge, no larger-than-life threat. They’re not even interesting as case studies in Muggle psychology, since their evil deeds have less to do with circumstances or choices they’ve made than with the fact that they’re all sickos. As a consequence, the suspense that powers this novel stems not from the mystery of the killer’s identity but from Ms. Rowling’s instinctive sense of storytelling and her wise decision to give readers frequent glimpses into Strike and Robin’s inner lives.