While attempting to get to a boat at the marina that will lead the group off the island, a big explosion occurs, forcing the group to retreat to safety. Soon after a secret is revealed leaving everyone in the group horrified.
After a dark secret is revealed, the group starts turning against one another. When another guest goes missing, however, the group is forced to come together to find them as well as Madison before it's too late.
The wedding guests prepare to leave the island, but when new evidence leads the Sheriff to suspect one of them is the killer they are forced to stick around. Some new information reveals an eerie connection linking Abby and Wakefield to one another.
It's Bachelor and Bachelorette party time. Henry and the groomsmen go fishing and discover something shocking, while Trish and her bridesmaids hang out with a psychic, who has a strong reaction to Abby.
When Abby isn't sure the ruling of girl's death as suicide is right, she challenges her father to investigate what really happened. Also Trish is still on the fence about Hunter, but finally makes a decision on what to do about him.
The wedding party has some fun while embarking on a scavenger hunt. Trish confronts an old flame, while Henry works towards making peace with some locals. Meanwhile, Abby runs into an old friend who is still being haunted by John Wakefield and the murders he committed.
Abby Mills returns to her childhood home, Harper's Island, for the wedding celebration of her best friend, Henry Dunn, and his fiance Trish Wellington. Abby has not been home in 7 years, since John Wakefield murdered her mother and 5 others.