First of the Summer Wine is a prequel to Roy Clarke's long running show, Last of the Summer Wine, portraying the youth of the principal characters from the mother show in the months leading up to World War II. With the possibility of war hanging over them, the young men and women enjoy their youth while trying to find a place for themselves in the world. The show used young, mostly unknown actors to play the characters, with only two actors from the original series making an appearance in the prequel
Compo is washing the windows at the Co-op store. Clegg, Seymour and Sherbet swap his bucket of clean water for one containing dirty water. Foggy's mother takes him to the Co-op to buy new pyjamas. Mr Scrimshaw suggests a pair 'with a stronger gusset'. Seymour is still pining for Deborah Norbury. Compo suggests a plan to help Seymour out. He'll jump out of hiding in front of the young lady, allowing Seymour to come to her rescue. The plan goes wrong when Compo jumps out in front of Mrs Norbury by mistake
The gang discuss the Co-op dance which took place the night before. Clegg is rather embarrassed because Anita Pilsworth from Accounts walked him home. Compo bemoans the fact that he can't foxtrot. He practices with a shop dummy, thus annoying Mr Scrimshaw. Wally is still failing to impress Nora with his new motorbike, mainly because it falls over whenever he gets off. Seymour declares his intention to become a fighter pilot once the war starts. He asks Foggy what qualifications he would need. Foggy says that he would have to be able to spin around at high speed. The lads spin him round in Mr Scrimshaw's office chair. He ends up dizzy and very unsteady on his feet. Mr Scrimshaw thinks he's been drinking. The gang go to the cinema. Compo has no money, so he tries to sneak in through a rooftop window. He ends up dangling in front of the screen and is caught by the commissionaire.
The lads are all feeling stiff after pushing a gypsy caravan belonging to Compo's mother. Anita Pilsworth is still chasing Clegg. Foggy is practising camouflage techniques. He's talked into pretending to be a shop-window dummy and he subsequently manages to startle Wally. Compo devises a plan to help Wally by dressing up as a gypsy fortune-teller and convincing Nora that she'll marry a "short miserable little nit wearing an LNER cap". All goes well until the caravan rolls away, dragging Compo past the girls and revealing the identity of the fortune-teller.
Deborah Norbury is unwell, so Seymour decides to take her a box of chocolates. He just needs to find a way of getting past her mother. Clegg's mother is upset because Mr Clegg's new Air-Raid Warden's uniform has arrived. It consists of an armband, a tin helmet and a whistle. With the help of the lads, Seymour tries climbing a ladder to Deborah Norbury's bedroom window so that he can deliver the chocolates. He only succeeds in scaring the young lady. Compo has been seeing Chunky Livesey's girl friend. At the cinema, Compo learns that Chunky is waiting for him outside. He manages to sneak out with Wally sitting on his shoulders, wearing a long trench coat.
The lads convince Foggy that they have 'borrowed' a dead body from the Co-op funeral service. It's actually Wally wrapped in a sheet. Mr Scrimshaw spends most of the day setting up a display of tins, only to see it collapse at closing time. At the cinema, Seymour learns that Deborah Norbury is upstairs in the circle. He goes up to see her but is tripped by Lena. He falls into Deborah's lap and she walks out on him. Compo is thrown out of the cinema. He tries to sneak back in through the window in the gents' lavatory. He manages to pull a cistern off the wall and gets soaked.
Dilys and Brad are getting married. The lads travel to the registry office on Compo's old motorbike and side-car, which keeps tipping up. At the reception, Compo has to sit with his trousers around his ankles because he's got oil all over them. Mr Clegg reads out the telegrams, one of which is from Brad's airbase, recalling him to duty. Later, the lads go for a walk and find Foggy guarding a bridge. He shows them his new bayonet, but manages to drop it into the river. Compo is lowered over the bridge using Seymour's long scarf. He falls in but manages to retrieve the missing bayonet. Next morning, war is declared on Germany.