Sam Davis is a struggling writer who has always carried a torch for his ex-girlfriend, Zoe. When he hears of her upcoming wedding to a famous documentary filmmaker, Whit, Sam sees an opportunity to win her back. He convinces Zoe's little brother, Marshall, to accompany him to the wedding weekend at the beachside estate where the nuptials will take place.
Once they arrive, Sam tries to charm his way into Zoe's affections, but she is already very much in love with Whit. Sam becomes increasingly desperate as the weekend wears on, coming up with increasingly outlandish schemes to sabotage the wedding. Marshall, who is dealing with his own unrequited feelings for Zoe, tries to talk Sam out of his self-destructive behavior, but Sam refuses to listen.
As the wedding day approaches, Sam and Marshall are drawn into the orbit of the eccentric guests at the estate, including a retired Hollywood actress and a former child star turned entrepreneur. Sam's behavior becomes more erratic, and he even attempts to rescue Zoe's beloved dog from the ocean in a misguided attempt to win her back.
Ultimately, Sam's actions drive a wedge between him and Marshall, and put him at odds with Zoe, Whit, and the other guests. In the end, Sam realizes that his obsession with Zoe was never really about her, but about his own deep-seated insecurities and fear of being alone. He makes a final, desperate attempt to win her back at the wedding, but is ultimately forced to face the painful truth that sometimes love just isn't enough.