Set in 1942 against the backdrop of World War II, and based on a true story, this eccentric tale begins in England at a backwater barracks, where Sergeant Peter King and Private Leslie Cuthbertson, our two protagonists, practice the art of dentistry. King, a Sergeant in the Army Dental Corps, has received one rejection too many of his request for frontline duty, and is fed-up with being a passive participant in the war. Similarly, Private Cuthbertson, a trainee dental mechanic, is bored by classes on dental hygiene and desperate to see action. This is a story about two men trapped in dead-end jobs, desperate to live out their dreams.
Cuthbertson comes to King's attention when he finds him playing with a grenade in the Armoury. Later that night after yet another rejection, Sergeant King wakes Cuthbertson and the two set off, on what Cuthbertson believes is a routine army exercise. It is only when King asks for his paybook to enclose with a letter to Churchill that Cuthbertson begins to understand King's plan. Cuthbertson has been enlisted by King to travel to France and fight the Germans. They are going to see some action and reek havoc. But first, they must travel to a small fishing port in Cornwall, steal a boat and sail across the Channel to France.
After a train and bus journey the men, laden with a rucksack full of grenades and dentistry equipment, eventually arrive at a small fishing port and are met by the local darling Emma Fraser. Smitten by Cuthbertson she persuades the men to stay overnight at her mother's pub. Reluctantly King accepts the offer, but is really only interested in getting a boat to cross the Channel and becomes annoyed at the flirtation between the young people. Cuthbertson reveals to Emma that he is on a secret mission.
A few failed attempts later, the men finally set sail. After a long and difficult journey they arrive on land, but quickly come to believe that they are back in Cornwall, when they hear two women chatting in English about cookery. But it turns out to be a radio transmission being monitored by a German Signals Officer. Although relived that they have actually arrived in France, the two men soon become disappointed at the lack of action and Cuthbertson is quick to criticise King and his promise of finding adventure. Nonetheless, King is on a mission and with Cuthbertson in tow proceeds with his haphazard plan. Eventually they come across a railway track and on King's instruction they follow the track. When they reach an empty station signal box, King enters, leaving Cuthbertson on guard. A German Signalman manages to slip past Cuthbertson and into the box, where King is forced to hit him over the head. Before they can work out what to do next, a train full of German soldiers approaches. They only just manage to operate the signals to let the train pass through the station without alerting suspicion. Relieved and exhausted the two men once again set off in search of some action, neither one of them knowing what the future holds.
King, desperate to maintain his hard exterior and rank, constantly belittles
Cuthbertson until the young man retaliates and the pair come to verbal blows. Gradually, both men begin to soften and we begin to understand why Cuthbertson looks up to King and why King is so insecure.
When the men finally come across a German radar base King produces a plan, which has Cuthbertson standing guard, while King goes under the fence to plant the grenades. Unhappy with his passive role, Cuthbertson challenges King, saying that he hasn't come all this way to watch someone else's action. King's response is that he believes that whoever goes in there will die. Cuthbertson eventually persuades King to involve him in the blowing up of what they believe is the main Operations Room. They set the bombs and soon the base erupts with gunfire and explosions, much more than either expected from their supply of weapons. For a moment King thinks that Cuthbertson has been caught in the gunfire but within minutes Cuthbertson appears on a motorcycle with sidecar and they make a rapid and narrow escape back to the coast.
The men eventually locate their boat and prepare to set sail once again. But their journey back to England is not destined to be easy. The boat is out of fuel and they have to start rowing. After losing an argument with a stray mine in the Channel, the two men are picked up at sea and taken back to England where they are interrogated as spies. Their identity is eventually established and they are labelled as deserters and taken to Aldershot Barracks to be court martialed.
In the meantime, King's letter to Churchill has found its way into the hands of Churchill's Chief Intelligence Officer, Major Merton, who tells Churchill about the proposed antics of our protagonists. It is believed that Churchill admired the tenacity of the men and instructed Major Merton to track the men's progress.
Luckily, just as the court is about to pass its verdict Major Merton intervenes and asks the men a series of questions, which prove that they were at the German Radar Station. He also tells the court that Sergeant King and Private Cuthbertson managed to create a useful diversion with their explosions, because on that very same night the Parachute Regiment were attempting to steal portions of the German radar equipment and bring it back to England for analysis. Major Merton also reports that the two men blew up the cookhouse and not the Operations Room as they had thought.
Exonerated of lying, King and Cuthbertson are reprimanded by the Court for their behaviour, but invited to tea with the Prime Minister should they ever be in Whitehall.
The two men never met again. Both achieved their aim of seeing active service. Sergeant King was decorated for bravery, ending his army career as a major and retiring to New Zealand. Private Cuthbertson transferred to the Durham Light Infantry and eventually became Deputy Mayor of Newcastle-upon-Tyne.