Monika (Harriet Andersson) and Harry (Lars Ekborg), young lowly stock room employees fall in love. Summer's near and after harassment at work and getting fired for being late, they run away to a remote island on Harry's dad's motor boat. For a while it's a paradise. They are in love and nothing really matters. No need to think about the future. Monika get's pregnant, supplies run out and soon they resort to stealing food from neighboring villages. In the end, they have to come back to Stockholm. Harry needs to get a job to provide and Monika's not satisfied with their less than glamorous life.
Andersson's youthful energy and insatiability for life is infectious and that's why that Monika staring into camera scene near the end is so chilling. She was slightly manipulative as any young pretty girls are, but there is something more pernicious in her eyes now. Her innocence and youthfulness is gone. Harry, now a regular boob, with the baby girl in his hand, pines for that glorious summer days. Bergman paints realistic picture of a Summer fling and its aftermath. It's not like in Hollywood movies that Monika likes. Summer with Monika plays out like an Italian neo-realist movie but has a more of a sinister edge to it.