Psychiatrist Haleigh Hugo thinks he's found the perfect setting for his experimental treatment plan -- an isolated home in the middle of a small lake in the high Sierras. Dr. Hugo's office mate and life partner, Guy Sanford, is unconvinced that the benefits of the treatment plan outweigh the risks, but soon gives in to the charm and boundless enthusiasm of his lover. Dr. Hugo's subjects are six female patients who have failed to make what he considers significant progress in one-to-one therapy. They all share something in common: grief over the loss of a loved one, a psychological barrier that prevents them from moving on. Hilary Colbert lost her life partner to a serious illness; Jennie Travers no longer trusts her unfaithful husband; Meeda O'Connell's infant son died in his crib; Vera Field wakes from a coma to learn her father has committed a senseless crime: Sarah/April Preston no longer knows who she is and suffers from a loss of identity; and Emily West has psychic abilities yet longs for a normal human existence. The six patients, overseen by Dr. Hugo and Dr. Sanford, descend on Devonshire, a simple mountain home on the lake for a weekend of intense therapy. Yet within the walls of the home lies a terrible and painful secret that haunts anyone who comes near.