Martha Armstrong has started again - new city, new home, new future. Yet she is troubled by her partner Will's obsession with the paranormal and unwelcome face from her past. Troubles which threaten the happiness she thought she had found. Her friend Gabriel McKenzie, a psychic medium, is troubled too - disturbed by ghosts he suddenly cannot see and haunted by one he can't escape. Who is the strange intruder that leaves him mysterious messages in his apartment and watches him sleep at night? So when a desperate call for help comes from Gabriel, Martha and Will make a decision to help him - a decision that take them north, to the bleak Highland of Dubhglas Castle and its lake, where mysterious occurrences are terrifying the staff. Could they be connected to Gabriel's nocturnal visitor and, worse still, to the powerful spirit of the brutal Jack Ball? Together, they uncover the secret that shattered Gabriel's family and split a young couple apart, fifty years before. Is it always best to uncover the past, or are some secrets best left lying in the Dark Water?