"The mermaids singing" by Val McDermid

An audio book.

A man on a tour around Italy goes to the torture museum in San Gimignano. It gives him ideas on how to kill again - if he needs to.

The police boss, Cross (old fashioned), denies that 3 macabre murders are related. His team don't agree. In the team are John Brandon, who has 3 teenage kids, and Carol Jordan, who's alert to being treated differently to the men. She lives with her brother, a computer whizzkid.

Dr Tony Hill (Home Office) gives a talk on psychological profiling, looking for clients. He's glad when Brandon approaches him. He realises that Brandon's boss is resistant. Carol is assigned to work with him. They're attracted to each other. The two confide about their previous relationships. He is inhibited sexually. His earlier research into telephone sex has led to him receiving calls from a woman - the calls help him. Policeman Don Merrick is asked by his (and Carol's) boss to report Carol's actions to him. He pretends to be gay, goes round clubs, and gets info. An innocent suspect kills himself. Cross is suspended.

There's a 4th murder. A policeman this time. The man has access to an empty farmhouse with a cellar (it was his aunt's). He chloroforms Adam and takes him to it. He makes a snuff movie. He's interested in the media coverage. He wants respect.

Tony starts analysing. We have a chance to see how accurate his hunches are, The victims weren't openly gay, but their bodies were dumped in gay haunts. He wonders if his own problems are the result of his work, or vice versa. Carol wants to sleep with him, but he goes cold. She hears a sexy message on his answerphone. She suggests to him that the killer might be female and that s/he might have access to the expensive software that her brother uses to manipulate videos.

Kevin, a policeman, is sleeping with Penny, a journalist. Leaks are becoming unhelpful. There's a 5th murder - copycat? Tony disappears.

We learn (1st person PoV) that the killer had a prostitute mother, that he had a sex-op abroad (still ugly face though), that s/he killed her mother, that s/he's the phone-caller, and s/he's tied Tony in the cellar. Tony gets his captor to trust him enough to give him a chance to kill the captor as the police arrive - Carol had pieced together the clues with the help of Tony's hunches. Tony and Carol end up mutually respecting their skills. Tony tells her about his erectile disfunction issues.

Again I like McDermid's writing, though the meticulousness of the criminal leads to some sections being longer than I'd like.