The Way Way Back tells the story of 14-year-old Duncan's (Liam James) awkward, funny and sometimes painful summer vacation with his mother, Pam (Toni Collette), her overbearing boyfriend, Trent (Steve Carell) and his daughter, Steph (Zoe Levin).

Although Duncan has a tough time fitting in and finding his place, he does find an unlikely ally and mentor in Owen (Sam Rockwell), a carefree employee at the local water park where Duncan gets a job. Over the course of the summer, as his mother drifts further away, Duncan, with encouragement from Owen, begins to open up and come into his own.