A small group of family and friends gathers on a secluded island to attend a weeklong wedding celebration... but the island’s history as the location of a mass killing threatens the joyous event and sets the stage for a new mystery.

Abby Mills (Elaine Cassidy), still haunted by the vivid and persistent nightmares of her mother’s murder, journeys home to Harper’s Island for the first time since the horrific event to celebrate the marriage of her childhood best friend Henry Dunn (Christopher Gorham) to Trish Wellington (Katie Cassidy), a beautiful, innocent and wealthy heiress. Neither the happy couple nor the wedding guests have any idea that returning to Harper’s Island will trigger terror and death to be added to the nuptial festivities.

Over thirteen episodes, Harper's Island will unravel a twisted tale of murder and revenge as these wedding guests – each with their own motives, fears and desires – must find the killer (or killers) before he (or she) strikes again.