Colin is a sex-starved young schoolteacher who owns a house in London. He dreams that a queue of beautiful blonde young women, all dressed in white, are waiting to see his lodger, Tolen. They don't notice Colin at all.
Colin has another room to let in the house, and hopes that someone will move in who can alleviate Tolen's influence.
Meanwhile, Tom is evicted from his bedsit for painting everything white. Innocent young Nancy arrives in the city from the north and starts looking for the YWCA.
Colin begs Tolen to tell him the secret of his success with women. Tom sees the 'room to let' sign and moves himself in, moving the furniture out and painting everything white, even the windows. Tolen is annoyed, as he had wanted his friend and mentor, Rory McBride, to have the room.
In her search for the women's hostel, Nancy is introduced to London - snooty shop assistants, women removing their underwear in photo-booths, friendly soldiers in Horseguards barracks.
Colin becomes increasingly desperate; watching the girls at his school play netball, he has a sudden vision of himself as a dirty old man in a raincoat. He thinks his luck will change if he gets a bigger bed, like Tolen's. Tom takes him to a junk-yard, where they see a huge old iron bedstead. Preparing to take it home, they meet Nancy, who is still searching for the YWCA, having been misdirected to Buckingham Palace.
All three wheel the bed through the streets, back to the house. Nancy is introduced to Tolen. A game is suggested - Tolen will be a lion tamer, with a whip. Colin, crawling around the floor with a carrier bag on his head, is the lion. Tom makes the tea. Nancy becomes excited and frightened by the game - and by Tolen, who demonstrates his 'knack' for Colin's benefit. When he has 'warmed' Nancy up, he turns her over to Colin, but Colin is so inept that Nancy gets bored and starts to leave. Tolen says he will take her to the hostel, and they ride off on his motorbike, with Colin and Tom in hot pursuit.
Nancy gets overexcited when Tolen makes a pass at her in the park, and she faints. The boys argue about who caused this, and Colin says that it couldn't be him, as he hasn't the knack to make a girl lie on her back on the ground in the rain. Nancy wakes up and loudly insists that she has been raped. Tolen is affronted at this insult to his technique, and Colin convinces himself that he was responsible. Nancy lets down the tyres on Tolen's bike and back at the house she throws his record collection out of the window. Tolen tries to reassert his influence over her but now she only has eyes for Colin.
Tolen and Rory McBride hold a reunion of their old girlfriends at the Albert Hall, but when Tolen arrives, nobody recognizes him. He has a further shock in store, when Nancy moves in with Colin.
