1946. Five-year-old Jim MacLaine's father returns home after being demobbed to work in the family grocery store. But he cannot settle down and, on a visit to the boating lake in a local park, he sets a trapped boat free and tells young Jim that he is leaving him and his mother. He walks out that night.

1959. Jim is at a boys' grammar school and about to take his 'A' levels. Mrs MacLaine wants him go to university like his studious pal Terry, but Jim is bored with studying history. Jim and Terry visit a café and chat up schoolgirls Jeanette and Jean.

Jim and Terry cycle to school for the exam. Stopping on a bridge, Jim throws his books in the river, does a bunk from the exam and leaves home. Hitching a lift, he arrives at a seaside resort and, after spending his first night on the beach, gets a job as a deck chair attendant and rents a room. After hearing from Jim, Mrs MacLaine pays a visit to the beach and pleads with Jim to return. Hurt, and with a strong sense of betrayal, she throws some cash at him and leaves.

Jim picks up two girls on beach and they visit a fairground. Later, a drunken Jim enters the closed fairground and is apprehended by an understanding policeman who doesn't arrest him. Terry comes to visit Jim and says he obtained 3 distinctions in his 'A' levels and is off to university.

Jim next secures a summer job as a holiday camp waiter, sharing a chalet with more experienced Liverpudlian Mike, who tells him how to 'pull the birds'. They successfully try this out. That night, Jim takes his girl back to the chalet, but his seduction is interrupted by a crying baby next door and he performs badly. However, Jim learns from experience and soon has many sexual conquests. At the camp jive contest, rock 'n' roller Stomy Tempest sings and Jim is impressed with his sexual charisma, and later chats to him and his drummer.

Out of season, Mike works on a fairground dodgems and he tells Jim how he fiddles customers out of their change. One customer who is swindled arranges for Mike to be beaten up. The ride owner offers Jim a job.

Terry invites Jim to a college dance, at which a trad jazz band plays. Terry introduces him to a girl student but they have nothing in common and she soon makes an excuse to leave. At the fairground, Jim meets a more likely prospect, who invites him back to her room. As they start to make love, her baby starts crying in the corner. Jim runs away in horror.

After two years, Jim returns home. His mother is bitter, comparing her drifter son with Terry's success. At a roller skating rink, Jim meets Jeanette again. Jim works in the family grocers, and acquires a delivery van in which he takes Jeanette out to the lakeside for a lovemaking session. Jeanette soon becomes pregnant, and she and Jim marry.

Terry warns his girlfriend Jean about Jim's promiscuity, but this does not prevent Jim also enjoying sex in the back of his van with her.

Jim, Jeanette and their baby live with Mrs MacLaine and Jim's ill grandfather. Jeanette is suspicious of Jim's wanderings, especially his so-called 'night school' activities.

Terry's parents and his girlfriend Jean visit the MacLaine home for an uncomfortable afternoon tea, with Terry's mother boasting about her son's achievements. Terry and Jean are planning to get engaged after Terry's final exams, but it is clear that she finds Jim more desirable.

Jim visits a cafe and chats to two youths performing in a rock 'n' roll band who are playing at Floral Hall that night. At the show, he notices the sexual allure that the lead singer has for females in the audience.

Jim walks by the lake in the park with his pram and returns a boat to a boy on the other side. He returns home, packs a suitcase and walks out on Jeanette, his baby and his mother.

In a music store window he sees a guitar and buys it.