Iain [M.] Banks - Complicity

Its two main characters are Cameron Colley, a journalist on a Scottish newspaper called The Caledonian, which resembles The Scotsman, and a serial murderer whose identity is a mystery. The passages dealing with the journalist are written in the first person, and those dealing with the murderer in the second person, so the novel presents, in alternate chapters, an unusual example of an unreliable narrator. The events take place mostly in and around Edinburgh.
Plot summary

Colley is a "Gonzo journalist" with an amphetamine habit, living in Edinburgh. He also smokes cigarettes and cannabis, drinks copious amounts of alcohol, plays computer games, and has adventurous sex with a married woman, Yvonne. He regrets his addictions and misdemeanours and tries half-heartedly to give them up occasionally.

He reflects on his awful experience of witnessing the aftermath of the massacre at the 'Highway of Death' in the Gulf War, and covers the deployment of HMS Vanguard, Britain's first Trident nuclear missile submarine.

He thinks he has a scoop when he receives anonymous phone calls about a series of mysterious deaths. Suddenly he has mysterious deaths of his own to worry about, when an editorial he wrote years before comes back to haunt him. In it, he suggested that certain named capitalist and right-wing public figures would be better hate-figures than the conventional ones of foreign leaders or domestic criminals. It seems someone is killing off the people on his list, one by one. The description of the murders (which are ingeniously sadistic) is done in a fairly detailed manner.

Under suspicion by the police, Colley finds himself involved doubly in the bizarre murders when the killer is revealed. At the end of the book, Colley is diagnosed with lung cancer (a downbeat ending omitted in the film adaptation).