As Ruth Rendell's final novel, DARK CORNERS, opens, readers meet Carl Martin, a young man who has inherited his father's house with everything in it. His dad believed in alternative medicine and left behind his "stash." Carl knows nothing about the pills and bottles of liquids he finds stuffed in the bathroom cabinet. He reads a few of the labels, and even though some say "caution," he puts them all back where he found them.

Carl is a struggling writer who recently had his first book published but is not seeing any royalties yet (or perhaps ever). A whole apartment exists on an upper floor, and he decides that a way to find money is to rent this space. He lists the apartment in the paper, and because of its fine location, several people reply to the ad. But for no particular reason, Carl rents the apartment to the first caller, Dermot McKinnon. They agree that the rent will be paid on the last day of the month, and Carl feels like a new man. What can go wrong?

"DARK CORNERS is a psychological thriller with many twists and turns along with well-limned characters. When you are sure you know what is going to happen, the story changes."

Then one day, Carl is out to dinner with his actress friend, Stacey Warren. She has gained a lot of weight and is worried about losing her leading role in a sitcom. It just so happens that a bag of 100 yellow capsules marked “weight loss” was one of the medicines Carl found among his father's concoctions. Finally, after some time goes by, he sells her 50 pills. Stacey is very happy to have these "DNP Dinitrophenol" capsules, but neither checks if any warnings are listed.

Nothing could go wrong in Carl's mind. He even asks his girlfriend Nicola, who has a job, to move in with him. She does, and all seems as it should be. That is, until Dermot does not pay the rent on time. Carl is in a tizzy about it, but later, when Dermot comes home from work, he knocks on Carl's door and hands him the money. They really don't have a conversation about it, and the following month the same thing happens. Now Carl is very angry and confronts Dermot. Nicola keeps encouraging Carl to stand up to this crazy tenant, but he can't do it. His writer's block is connected to all of these happenings. Time passes slowly for Carl, and he has no income except for Dermot’s rent money.

One day, a friend of Stacey's lets herself into the apartment with a key that was hidden in the staircase. She finds Stacey on the floor dead, lying in a puddle of yellow capsules. She calls the police who, after an inquest, find that no foul play led to her death. Carl can't believe what has transpired, and in his head takes responsibility for killing her. Dermot figures out the circumstances and starts blackmailing Carl by not paying the rent. This sends him into a depression, and he is at a loss as to what to do. The way he solves his problems may take the reader on an odyssey that is quite unexpected.

DARK CORNERS is a psychological thriller with many twists and turns along with well-limned characters. When you are sure you know what is going to happen, the story changes. Ruth Rendell, a world-renowned mystery writer who died earlier this year, has left behind an enormous body of work for all to savor.