You are cordially invited to a wedding on Harper's Island. But what is supposed to be a lively week of celebration takes a deadly turn. Beautiful heiress Trish Wellington (Katie Cassidy) and her betrothed Henry Dunn (Christopher Gorham) have invited their diverse group of friends and family to their nuptials on the secluded island. Although the locale is charming and romantic it has a sinister past. Seven years ago, six people were gruesomely murdered by the killer John Wakefield, including the mother of Henry's best friend; Abby Mills (Elaine Cassidy). As the "big day" approaches, secrets are revealed, relationships are tested and guests are being murdered, one by one. As victims start to outnumber suspects, who will be revealed as the killer?