The sounds of a train driving along a track opens the film, and bleed into music throughout. The camera tracks down the aisle of a carriage, passing commuters and other passengers seated on the train, reaching a man reading a newspaper, upon which the title of the film, "Strange Behaviour", is printed.
Inside a Sussex home, his wife takes ready meals out of their packets and puts the packaging in the bin. The man's train arrives at the station and he alights, passing under a walkway and playing field. His walk home is intercut with details of his suburban home, including the gold taps and oven knobs, and his wife applying perfume. He stops in his tracks, seeing a woman under a tree in period costume, gazing towards a lake in a park. She smiles at him. As he reaches the front door of his house he throws his briefcase and suit in the air. He is seen running through a field, tossing his shoes and trousers away, the town in view below. He throws hay into the air. Policemen arrive at his house. His wife is smoking inside. She stubs out her cigarette and opens the door to the men, holding her husband's belongings folded neatly in a pile. She takes the clothes and closes the door, calmly tipping the pile into the kitchen bin. Back in the field, a combine harvester passes and the man, now only wearing underwear and a beard, emerges, gathering hay to make a bed in a tree. Lying back in the nest, he is still uncomfortable. He steals chicken feathers from a farm to make his nest comfortable and lies back contented. The young woman he saw in the park walks through the field with a parasol and basket, stopping to rest and read her book below the man's nest. He jumps down. Scared, she starts to run away but he begins to perform animal courting display rituals for her. He flexes his muscles, walks like a peacock, shakes his head like a horse and jumps in the air. They are seen cartwheeling towards each other, and curling their necks together like giraffes. This sequence is intercut with footage of the animals, the couple imitate. The couple sit in the nest, gazing at each other, the young woman now pregnant. And suddenly, the fantasy is over. The man is seen back at the lake, walking home to his wife.