People are animals and the conflict that results between civilisation and a basically animal nature may be demonstrated by the frustrations of young people motivated by strong sexual impulses. Ingmar Bergman's 1953 film Summer with Monika (Sommaren med Monika) may be seen superficially as a condemnation of sexual indiscretions--this being a moral stance typical of Hollywood films of the time--yet, really, Bergman is portraying fundamental problems without the handicap of simplistic solutions. It's beautifully shot and features an amazing performance from a young Harriet Andersson.
As Monika, she's a teenager, the eldest child in a tiny apartment where her little brothers create daily havoc and sometimes fetch cigarette butts from her coat for her. At work, in a produce stockroom, her co-workers seem to know her as a loose girl and their behaviour towards her would constitute sexual harassment even by 1950s standards. Their treatment is a mixture of flirtation and punishment and despite being a girl who likes sex she's clearly only annoyed by the hypocrisy. One co-worker nearly rapes her until she screams and manages to push him away at which point he laughs as though he's only playing.
She picks up Harry (Lars Ekborg) in a tavern--he's a naive rich kid who seems like he's just starting to look at girls. They go to the movies and then have a tea date at his house but they're interrupted by the arrival of Harry's father just as they're starting to make out. The bulk of the movie covers an adventure the two have over the summer as they steal Harry's father's boat and live off what they can steal along the river.
So they escape from the confines of society and live to sate immediate physical urges. Monika takes charge of the shy, more childlike and simple hearted Harry.
Ekborg as Harry is a bit bland but good enough. As for Andersson, it's easy to see why Bergman cast her so frequently in later films. Her unrestrained acceptance of her character's nature helps the film to display the transcendence of popular, puritanical morality. In some ways, it reminds me of G.W. Pabst's Pandora's Box where the hyper-sexual character Lulu played by Louise Brooks drags to ruin all the people who care about her while nevertheless coming off as innocent and affectionate, like Monika, an uninhibited sexual being who was born in the wrong world.