In 1924 Boston, private investigator and war veteran Edward Pierce is a troubled man, plagued by disturbing nightmares he tries to dull with drink and pills. He takes on what seems like a routine case, looking into the deaths of the Hawkins family, who perished in a mysterious mansion fire. The only real clue is an unsettling painting made by the wife, Sarah, shortly before she died. The trail leads Pierce to Darkwater, a remote and superstitious island community wary of outsiders, where his investigation begins to unravel far stranger and darker truths.