Trevor moves in with his girlfriend Jill when his flat is torn down to make way for a new road. He brings with him his thousands of jazz records and tapes. Feeling swamped by his belongings, they go out for a drink. At the pub, Trevor befriends John, the barman. John is also a jazz buff and promises to make Trevor some tapes from his record collection.
At school, Trevor is stopped by Mr Wheeler, the head master, who is looking for volunteers for a trip to Holland. Trevor and Jill are convinced that none of the children will want to go and that it will be called off. Trevor receives the pack of tapes from John and discovers among them a recording of men talking. Listening to it, Jill realises that it contains the plans to secretly dump nuclear waste in the Yorkshire dales. Shortly afterwards, Trevor finds that their house has been searched. They go to the pub to find John, but are told that he has died in an accident.
Jill and Trevor return home and are confronted by a man from Special Branch who calls himself Peterson. He threatens them and demands to know where the tape is. Jill convinces him that she threw it in the canal. When Trevor later asks her where it really is, she will only say that is it in a "safe place". Trevor goes to the cemetery to find out when John is going to be buried, while Jill visits an old people's home to see her elderly friend Sylvia for some advice. Sylvia tells her that she must do something to flush the enemy out.
At school, the headmaster tells Trevor and Jill that he has received complaints about the fact that they are living together despite being unmarried. To make amends he makes them promise to take part in the trip to Holland. They are dismayed to discover that all the pupils in their classes are signing up for the trip as they consider the couple daring for 'living in sin'. Peterson returns after intercepting a tape that Jill posted to her uncle Jack. After checking up on them, he is now convinced that she would never throw the tape away. Despite his threats, Jill refuses to tell him where it is. He plays the tape he intercepted back at his office, but it is only a recording of George Formby songs.
