A decent and happily married man, Derek Cartwright finds himself dreaming of murdering his resident mother-in-law. And when by chance he meets the repellent Hugh Packer, a stranger who is also lumbered with an elderly dependent, what had merely been a midnight fantasy suddenly seems a practical possibility. Like latter-day 'strangers on a train', they could swap murders. That is Packer's idea, anyway: 'You've got a problem, I've got a problem, and together we've come up with the perfect solution. The sooner we get the jobs done the better.' Derek Cartwright knows he can never bring himself to murder anyone - not even an old man incapacitated by a stroke. But each time he thinks of his mother- in-law and how her presence in their home distresses his wife, he finds Packer's proposition more difficult to resist. After all, he only has to leave the old lady alone one evening - perhaps by taking his wife out to dinner. But then, there is the family beagle to be got out of the way . . . And that proves only the first of Derek's unnervingly difficult tasks, as he tries to set up a scenario that will deceive Detective Chief Inspector Quantrill of Breckham Market CID. Sheila Radley's dark and gripping story traces the descent of an upright husband and citizen into blunder, terror, nightmare, and murder.