A group of family and friends arrive on a ferry to jet across to Harper's Island for the wedding of Henry Dunn and Trish Wellington. As the groomsmen prepare for general debauchery, Henry's old childhood friend, Abby Mills, shows up in a cab. Abby tells the cab driver that she hasn't been back to the island in 7 years. Henry and Trish are very happy to see that Abby made it to the boat in time. Trish wants to get the boat moving but wonders where her cousin Ben is. She tries calling him but receives no answer and decides to head on to the island. Unfortunately, Ben is tied under the boat and when the propellers start, Ben is soon dead.
Some people are gossiping about Abby. Seven years ago, her mother, along with 5 other people, were murdered by a man named John Wakefield. Abby's father, the sheriff, killed Wakefield and sent Abby away.
Henry's Uncle Marty notices a young blonde named Chloe Carter. Chloe is on the boat with her boyfriend, Cal Vandeuson. Trish receives a phone call from a man named Hunter Jennings and ignores the call. Later, Trish's father, Thomas Wellington, receives an email from HJ regarding his daughter. Henry is very happy that his brother, J.D. Dunn, has come to celebrate his wedding, since both of their parents are dead.
Once the boat is docked, Abby runs into Jimmy Mance, who she was familiar with when she lived on the island. Jimmy is very happy to see Abby. The wedding party departs for the resort and Abby decides to walk. Meanwhile, Jimmy tries to help detangle some lines on the ferry and they are very close to discovering poor cousin Ben's head, but they miss the gruesome sight. As Abby walks, she passes a tree and flashes back to her mother hanging there. Luckily, Henry shows up and says that they should have cut that tree down long ago. Henry walks her back to the resort.
At the resort, a welcome dinner is planned. As the guests get ready in their rooms, Cal and Chloe enjoy some fun in their room. Cal has a surprise for his lady love, a diamond engagement ring. The girls in the wedding party are shocked that Abby and Henry have never hooked up since they are such good friends. When Henry realizes that his brother is not at the dinner, Abby decides to go in search of him and heads to the Cannery, a local bar. Abby finds J.D. at the bar and also runs into Jimmy who challenges her to a game of pool. When J.D. talks to a girl, her ex-boyfriend starts a fight and the cops are called. Sheriff Mills escorts both J.D. and Abby back to the hotel.
Trish receives a text message from Hunter, who is on the island and he asks to meet her. Trish meets him in the lobby and he tries to kiss her and wonders if she is making a mistake. Trish tells him that she is marrying Henry. Later, Uncle Marty catches Hunter talking to Mr. Wellington. Seems Trish's dad doesn't want his daughter marrying Henry either and is trying to break up the nuptials. Later, Uncle Marty slyly threatens Mr. Wellington.
Elsewhere, Chloe and Cal decide to go swimming and Cal leaves the diamond ring in his pants. Chloe pretends to be drowning. He goes to help her and she pulls him under the water. When she resurfaces, laughing, Cal is so angry that he holds her head under water. Chloe is furious and storms out of the water and throws Cal's clothes into the ocean. Cal is very upset when he realizes that the ring is missing. Elsewhere, Henry and Trish are enjoying post coital bliss and Trish jumps up to take a shower. Trish yells that they should have separate rooms until the wedding. Henry sees a call come into Trish's phone and sees that it's Hunter and looks worried.
Uncle Marty takes a walk after his talk with Mr. Wellington. As Marty is passing over a wood bridge, one of the planks gives way and he falls half way through and gets stuck. Marty hears someone underneath him and calls for help. Suddenly, Marty is stabbed. Having a gun on him, Marty starts shooting below, but misses his assailant. The unseen assailant continues to stab Marty until only half of him remains stuck in the bridge.