Abby Mills returns to Harper's Island for the wedding celebration of her best friend, Henry Dunn, and his fiancée, Trish Wellington. Abby hasn't been home in seven years, since her mother and five others were murdered by John Wakefield.
As the wedding party embarks on a scavenger hunt, Trish confronts an old flame, Henry makes peace with some locals and Abby runs into a friend who is haunted by John Wakefield and the island's tragic past.