Duncan (played by Liam James), an ordinary fourteen-year-old, anticipates his family vacation with little enthusiasm. He’s not eager to spend time with his mother, her boyfriend, and his step-sister. Seeking escape from this seemingly perfect situation, he goes to the "Wizz" water park where he connects with one of the animal caretakers, Owen (Sam Rockwell). Owen recognizes something familiar in the younger boy and lets him assist with his work. Over the course of the summer, they each provide support as the other confronts personal struggles—and eventually, a more self-assured Duncan begins to take shape. Although the film isn’t exceptional, Liam James's compelling and likable performance is reason enough to see it. His adolescent frustrations are portrayed with intelligence and nuance, and his connection with Rockwell, who becomes an unlikely friend, develops gradually, sometimes in challenging ways. The movie suffers from excessive talking, and I felt that the storyline involving his controlling step-father, Trent (Steve Carrell), and his incredibly annoying daughter, Steph (Zoe Levin), detracted from the core story of connection and growing confidence. It's still worth seeing.

Source on TMDB