Duncan (Liam James) is a shy, awkward 14 year old. His mother Pam (Toni Collette) is dating a car salesman named Trent (Steve Carell). Trent means well but he seems to think that the way to bond with a 14-year-old boy is to constantly tell him to shape up. He means well but…oh what can I say, Trent is a jerk. Trent has a daughter named Steph (Zoe Levin) who is about Duncan’s age but much more mature. She thinks Duncan is totally embarrassing to have around.
His mother wants all of them to get closer so they pile into Trent’s classic station wagon and head off for a vacation at his summer cabin in a beach community. They are greeted by Trent’s neighbor, a brassy blonde named Betty (Allison Janney) and her children, alienated Susanna (AnnaSophia Robb) and her geeky little brother Peter (River Alexander). Susanna is the same age as Duncan and actually seems interested in him, but he is much to shy to do anything about it.
Duncan is pretty miserable at first but things start to look up for him when he encounters Owen (Sam Rockwell) the manager of a run-down water park with the unfortunate name of Water Wizz. Duncan finds that he enjoys hanging out with the assorted misfits who work at the park. He ends up taking a part-time job there–without telling his family.
It’s all fairly low-key. There’s fair amount of horseplay, nothing particularly distasteful. Nothing happens that could be considered particularly tragic or life-changing, but Duncan seems to end up a bit more mature and self-confident so I guess that’s fine.