The new Sam Blackstone adventure - It is a worried letter for Tom Yardley, an old army comrade who once saved his life, that takes Inspector Sam Blackstone to the salt mining village of Marston. But by the time he arrives there, Yardley is already dead blown to pieces in what was apparently a freak accident. Acting strictly unofficially, Blackstone begins to investigate Yardley's convenient death. It does not take him long to realize that there is true evil lurking in and under the village . . .