George Keating, a naive, young writer, has his life sidetracked when he catches “the love of his life,” Nicole, making out with her favorite coworker, Jerry. When Nicole sees that she has been caught, she breaks up with George on the spot.
Ten months later, George is still a mess from the breakup. His crying sessions constantly wake up his roommate Nicole’s brother Jeff, who, fed up with losing his eight hours, kicks him out of the house for the night. This forces George to go to his hideaway: an old lifeguard tower on the beach. This is where he meets Mystery, a woman who brightens the world around her. She attempts but fails to coax George out of his emotional funk. She flirts, makes jokes, and eventually convinces him to swim in the ocean with her, resulting in the two of them being together until sunrise. Unbeknownst to George, throughout the night, Mystery develops feelings for him. George rushes home and tells Jeff that he has come up with a plan to get Nicole back with the help of Mystery. Jeff suggests that he ask Mystery out instead since George can’t stop raving about her. George explains that Nicole is his soulmate so he can’t be with anyone else.
The next day, George tells Mystery about his situation with Nicole and asks her to come to a party with the added catch that Mystery could help him get her back. Mystery is deflated by this but eventually gives in and agrees to help.
On the day of the party, George tells Jeff about his plan and he assures George that it will work. Jeff secretly hopes that the plan will embarrass George to the point that he will finally realize he needs to move on from Nicole. That night at the party, the apartment is packed but Nicole is nowhere to be seen. George is distraught but Jeff tells him that she’s always fashionably late and is surprised George doesn’t know this considering the amount of time the two dated. Nicole and Jerry arrive which makes George pass out from his anxiety, forcing Jeff to drag him into his room. Just as George is dragged out, Mystery arrives.
In his room, Jeff admits to George that he doesn’t think Nicole is right for him and that George deserves better. George dismisses this, saying he is still in love with Nicole. Suddenly, George gets a text from Mystery letting him know she’s at the party and he runs out to meet her. The two of them force their way through the crowd to Jerry and Nicole, but before George can set his plan in motion, Nicole takes Mystery away to the bar. Once there, Mystery learns about George’s breakup from Nicole’s perspective and that she is only with Jerry for all that his large paycheck can buy. Nicole tells Mystery that she should be into someone else as George is not good enough for pretty girls like them. Then Jeff joins them to greet his sister but Nicole believes that he’s the real person that Mystery has eyes for and leaves the two of them alone. Jeff tells her that he hopes George will finally move on from Nicole after the party and admits that his sister is not the nicest. Jeff also lets Mystery know that he thinks George has feelings for her which makes Mystery realize that it’s time to let George chase her.
Mystery tells George that she’s leaving but he pushes back. She angrily announces she is leaving and walks out in a huff. Jeff takes that as his cue to shut down the house party. That’s when George sees Nicole and Jerry leaving and chases after them. He catches up to Nicole and Jerry outside but soon realizes where his true feelings are, with Mystery. Jeff advises George to be careful with his words but George immediately tells Nicole to f off for how horribly she treated him during their relationship and goes off in search of Mystery.
George finds Mystery at the same lifeguard tower where they met. She asks why George had her go along with his plan and George admits that he was scared of losing Jeff as his potential brother and that he was too focused on what was and wasn’t thinking of what could be. Mystery accepts his apology but teases George about the party she had to endure. George admits his mistake and tells her that he is over Nicole. Mystery is elated to hear this news and asks him to tell her how he said goodbye to his ex. As George recounts the epic moment Mystery puts her head on his shoulder. George puts his arm around her and says, “I have so much to tell you.”