Glasgow DJ Alan 'Dicky' Bird is distraught when his girlfriend Maddy walks out on him. His best friend Colin tries to cheer him up, saying that most people their age would give an arm and a leg to start a new life.
Alan tries to rebuild his life, but he keeps passing women who resemble Maddy, notably one serving ice cream in a Mr Bunny van. He follows it, buying an ice cream when it stops. As he's walking back to his car, two men in balaclavas smash up the van. One of them recognises Alan and demands an autograph before driving off. Alan goes back to the van and offers to help, but they're clearly in a hurry to get away. That night, he has a vivid dream about Maddy returning to him.
The next day, he opens his car to find several upturned ice-cream cones on the back seat and a note warning him to steer clear. After his show (the Dicky Bird Early Worm Show) and a frustrating session recording Thrifty Pops jingles, he goes to see Hilary, his boss, and asks if he can make an investigative documentary. Hilary is unsure, using a metaphor about being caught above the waves while transferring between ships. He thinks Alan's depressed, but gives him the go-ahead anyway. But after Alan leaves, he asks his secretary to dig out his contract to see when it expires.
The next day, Alan is told that he will be met in the car park after work. He follows a Mr McCool's ice cream van to a large building. Getting out, he is introduced to Bruno, his brother Paolo and Renato, and is invited inside to meet Mr McCool. McCool explains that there's a system of unwritten territorial rules that Mr Bunny has been flouting. McCool wants Alan to talk to Mr Bunny to make him see reason, because as a respected DJ people trust him. He gives Alan a guided tour of the factory and a souvenir tub of ice cream.
After asking Mr Bunny to get in touch with him over the airwaves, he spots a Mr Bunny van and follows it to be Mr Bunny's headquarters. Mr Bunny, whose real name is Trevor, asks Alan if he has any idea what he's getting into. McCool wants to drive him out of business by controlling every franchise. He tells Alan to tell McCool that they'll sell his ice cream but under his conditions. Alan is given another souvenir tub of ice cream.
Alan meets McCool and family in a café, but refuses to reveal Mr Bunny's location. He lets slip the name Trevor, which gets an excited reaction - it turns out that he's a fish and chip seller who moved into ice cream without permission. Alan also reveals that he was given a tub of ice cream. Paolo asks if McCool can taste it, as he can identify any ice cream. Alan refuses - but that night the ice cream is stolen from his fridge.
After hearing another of Alan's coded messages to Mr Bunny, Hilary summons him to his office and recommends that he sees a psychiatrist, banning him from the airwaves unless he agrees. The session goes badly, and collapses completely when Alan uses Hilary's metaphor about being stranded between ships. The psychiatrist claims that was his experience, and is furious that someone else has stolen it.
Alan goes to see Trevor to warn him that McCool has his ice cream recipe and can track him down. Trevor says that it was McCool's recipe in the first place. McCool's men rush into the building and trash the place. A livid Trevor accuses Alan of betraying him. Before fleeing, Alan discovers that Trevor's girlfriend Charlotte is McCool's daughter.
Alan discovers that Hilary's wife makes ice-cream fritters, apparently very successful in China. He arranges a meeting between Trevor and McCool, and tells them about how successful ice-cream fritters are in China. They love the sample he makes for them, but Alan insists that they work together and give him a cut for handing over the recipe.
Alan sits in a nearly deserted radio station and wishes all his listeners a merry Christmas.
