Joe (Martin Potter), Sue (Julia Foster) and Barry (Nicky Henson) meet as strangers at a noisy wedding reception held in a poorer area of London but become boisterous friends and leave the reception with a bottle of champagne for an impromptu picnic on the Thames Embankment.
Barry doesn’t know Joe is a policeman, and Joe doesn’t know Barry is planning a robbery. But it soon becomes obvious that they come from two different worlds – Joe with his Grammar School background and Barry with his history of small crime and illusions of big money.
The only thing they have in common is Sue, and it soon becomes clear that she is torn between the kind of men she falls in love with and the kind of men she always ends up going home with.
But when Joe – feeling guilty about the afternoon’s unfaithfulness – goes home to his wife and baby daughter instead of staying with her, she becomes disillusioned and turns her affections to Barry, moving in with him.
Barry’s friendliness towards Joe also quickly turns to inbred hostility when he discovers that he is a policeman.
It’s not long before Sue becomes aware of Barry’s plan to hijack a cigarette shipment from a local warehouse. She sees him humiliated by the fence, Sonny Wade (Ian Hendry in an all-too-brief cameo) and sees the tension churn Barry’s stomach in nervous, painful anxiety.
Sue has been around but has never been directly involved in something like this. She tries to talk Barry out of the robbery, but in the end, it is Barry who talks Sue into waiting, suitcase packed, in his car, ready to drive away with him after the robbery.
Meanwhile, Joe is going about his duty as a London bobby – sorting out a domestic squabble, working on a theft charge at the local nick, and then being called in on his Sunday off for special duty at a demonstration.
A routine day – except for a warning that there might be a raid on a cigarette warehouse on his beat.
Dawn is breaking on Monday before Joe finally makes his way home, very tired and bruised from the demonstration. In the still, quiet of the hour, he notices the warehouse gates are open and goes in to investigate.
Barry has completed the robbery and is ready to drive off, but he sees Joe for the first time in uniform, and suddenly, the two young men are face to face, recognising each other and their violently opposed worlds.
In a desperate bid to get away, Barry accelerates to drive off. Joe smashes the windscreen with his truncheon, and the lorry swerves and buckles against the warehouse wall.
Barry panics and takes up the shotgun he has brought on the raid. This is the moment of truth for them both!
Produced by Carry On stalwart Peter Rogers for Pinewood Studios (with a musical score from Gerald Thomas), the film features lots of location shooting around Battersea in South London, highlighting how much the area has changed since the early 1970s.