In a deep valley in the Peak District of England a reservoir built in the 1940s empties during a long drought. When the remains of the drowned village of Bailsford emerge from the water they awaken painful memories for one old lady, Alice Lammas. It is a harrowing tale that Alice tells her grand-daughter, Mary Marquis, of her last summer in that village when she was only seventeen.
The emptying reservoir casts its dark shadow over Mary too, for the retreating water reveals a body, clearly murdered several years ago. But whose body? It is a question that becomes agonisingly important to Mary as her own well-ordered life begins to unravel.
Seeking consolation in her grandmother's story, Mary learns a remarkable secret – what lies buried beneath the sterile mud that now covers the abandoned village churchyard. And there is more. Alice's revelation forces Mary's grandfather, Frank Lammas, to tell a much darker secret that has haunted him for over 60 years.
Mary's world is shattered when an unwise decision has disastrous consequences, leaving her reputation and her career in ruins. Out of despair comes a reckless plan that almost costs Mary her life, but allows her to rebuild the one relationship that can secure her future.
Two tales in one, The Devil You Know brings Alice's and Mary's stories together vividly and dramatically, with many twists and surprises on its way to a hopeful ending.