A chance meeting in a coffee shop between Harry (Lars Ekborg), a young errand boy, and Monika (Harriet Andersson), a wild and reckless girl who works in a nearby grocery shop, soon develops into a love affair. After a row with her father, Monika goes on a motorboat holiday. Their idyllic summer is soon shattered by the news that Monika is pregnant. Faced with sudden responsibility, Harry agrees to marry Monika and they set up home together in a small flat. Monika rapidly becomes bored with married life and looking after the baby. Soon Harry returns from a business trip to discover that his wife has been unfaithful with a former lover. A frank and tender portrait of first love, Bergman's film is also a realistic and uncompromising account of a disintegrating marriage.