Iris Rukka, Kati Outinen, lives with her middle-aged mother and stepfather, a quiet home where the television news is a constant backdrop. They rely on her earnings from the match factory’s production line and expect her to handle all the housework. She goes to dances, but she struggles to find partners, and she hopes a bright, highly colored dress might change her luck. When they see the dress, her parents brand her a whore and demand she return it, yet Iris defies them and wears it to a bustling dance club.
At the club, Iris meets Aarne, Vesa Vierikko, who assumes she is a prostitute because of the dress—an assumption Iris herself doesn’t realize she’s provoking. They spend the night together in his plush apartment, and Aarne leaves before Iris wakes, leaving money on the bedside table. Iris leaves her number and, after waiting in vain for a call, visits him and arranges a second date. When Aarne finally calls for Iris, he invites her to dinner with his parents, but he bluntly tells her he does not seek her affection and asks her to leave. She returns home and spends the rest of the evening in tears.
Later Iris discovers she is pregnant and writes to Aarne asking him to raise the child with her. His reply is a cold perfunctory message: “Get rid of the brat,” accompanied by a cheque for 10,000 markka. Iris is distraught and leaves both letter and cheque on the table, where her mother finds them. While wandering in distress, Iris is struck by a car and suffers a miscarriage. Her stepfather, Esko Nikkari, visits her in the hospital and tells her she must move out of the apartment since she has caused her mother great pain.
Iris then moves in with her brother, Silu Seppälä, and sinks deeper into despair. She buys rat poison, mixes it with water, and places the mixture in a small bottle she carries in her handbag. She goes to Aarne’s apartment, asks for a drink, and when he goes to fetch ice, she pours a portion of the poison into his beverage. Before leaving, she tells him that everything is taken care of and that this will be the last time he sees her. She returns his cheque, downs most of her own drink, and walks away while he sits in stunned silence.
On the way home, Iris stops at a bar, orders a beer, and sits reading. A man sits beside her, uninvited, and tries to draw her into conversation. Iris smiles at him, takes out the poison, and pours some into his glass, then leaves, and the man finishes his drink.
Iris later visits her mother and stepfather, preparing a meal for them before pouring the rest of the poison into their bottle of vodka while they are next door. She sits in the living room, smoking and listening to music, and after a time, she rises to check and finds her parents dead. The next day, Iris is taken away by the police at work, bringing the troubling events to a dramatic and final moment.
