Perennial commitment phobe Jason (Zac Efron) and his co-worker Daniel (Miles Teller) are determined to help their devastated friend Mikey (Michael B Jordan) after he discovers his wife has been cheating on him. In a bid to cheer him up, the guys decide to take him out for a night on the town where united, they agree to make a pledge to bachelorhood.
The next morning a confused Jason wakes up to find himself in the bed of Ellie (Imogen Poots) and dubious of the circumstances of their rendezvous, flees the scene. When Jason & Daniel walk into an important work presentation only to find Ellie is a potential client, he desperately tries to explain the reason for his vanishing act and embarks on a mission to make it up to her, and in the process wins her heart. Meanwhile, Daniel and gal pal Chelsea become more than friends, and a heartbroken Mikey, rekindles the passion with his wife.
As the three men desperately attempt to keep their relationship a secret from one another, things become complicated, and they are forced to look at their relationship with their partners, and each another.