Plot

Comedy drama based on the true story of two British Army dentists who in 1942, eager to see action, go A.W.O.L. and invade occupied France on their own.

Based on a true story, Sergeant Peter King of the Army Dental Corps, too old to fight, and Private Leslie Cuthbertson, a trainee dental mechanic in the Corps, are thrown together by their passionate desire to see active service. Armed with just two revolvers and a dozen grenades, King persuades Cuthbertson to join him on a mission to occupied France. In a letter to Sir Winston Churchill, King explains their intention to invade France and fight the Germans. After several failed attempts, they finally arrive by boat and stumble across a German radar station. They succeed in blowing up what they believe to be the main Operations Room, but are soon forced to make their escape as the entire compound unexpectedly erupts with gunfire and explosions. After narrow escapes from the Germans and a stray mine in the Channel, the two men are picked up at sea and interrogated as spies. Identified as deserters, they are returned to their barracks to be court-martialled. At the last minute King and Cuthbertson are saved by the arrival of Major Merton, Churchill's Chief Intelligence Advisor. Their letter has been received in Whitehall and Merton corroborates their heroic story. Exonerated of lying, King and Cuthbertson are nevertheless reprimanded by the Court for their behavior, but receive an invitation to tea with the Prime Minister should they ever be in Whitehall.—Ira Trattner

In February 1942, Sergeant Peter King (Kenneth Cranham) and Private Leslie Cuthbertson (Leo Bill) of the Royal Army Dental Corps passionately desire to see active service, but are held back. Leslie watches numerous propaganda films where British commandos raid German installations and make meaningful contributions to winning the war. It is very difficult for them to see how the Dental Corps will ever contribute to winning the war. Their motto is "An Army that cannot bite, is an army that cannot fight".

Leslie goes into the company armory and picks up a grenade when the company Sergeant King follows behind him. The Sergeant takes the grenade but ends up pulling the pin. Leslie straightens the pin out and reinserts into the grenade, but the grenade ends up exploding, taking the whole armory with it. The company Major Bates (James Fleet) & Col. Hatchard (Julian Glover) believe it was hit by a 550-foot, German bomb. King tells Leslie that the army doesn't need him to fight, but to follow orders like the rest. Secretly, King also wishes to serve his country in active combat. King's request for a field posting is denied.

King wakes up Leslie in the middle of the night and explains the situation. Armed with two revolvers and a handful of grenades, they plan an unauthorized mission to occupied France and the town of Brest, where they intend to destroy the pocket battleships Scharnhorst and Gneisenau. They write to the prime minister, Winston Churchill (David Ryall), explaining their intention to fight the Germans and they send their pay-books along with the letter for identification. As such, they are Absent Without Leave or AWOL.

They hike to the nearest train station and catch a train to Cornwall. King explains that one grenade in the oil-driven steam turbine of the battleship would be enough to cripple the entire battleship. King was travelling with weekend leaves papers to address any suspicions in England. On their way, they learn that their target ships have already sailed from Brest. King decides to go to Saint-Nazaire which is a base for German U-Boats.

In the bus, Leslie strikes a conversation with a woman named Emma (Rosanna Lavelle), who takes them to the harbor. Leslie says that he is visiting the town with his sergeant to meet his niece. Emma offers that they can stay at her mother's pub, but King wanted to leave that night by taking a boat from the harbor. They try sneaking out at night and commandeer a boat, but the tide is out, and they cannot get the boat out of the harbor. Emma invites Leslie for dinner and it is clear that she wants to have sex with him. Emma is distraught to see Leslie leave.

In the English Channel, their tiny boat gets lost in the fog and is almost destroyed by an oncoming warship. When the fog clears, the soldiers believe that they have circled back and reached Cornwall as Leslie can hear women talking in English. But turns out they were in France when King notices a German radio man listening to English cooking broadcasts.

After they finally succeed in getting to France, they engage in small time sabotage like cutting telephone lines. Leslie goes into a barn to get supplies but is captured by a French woman. Before King can arrive to help, the woman gives Leslie a pie and has sex with him. King is livid with Leslie for sabotaging the operating, but Leslie says that he has followed every order given to him and yet it has got them nothing and now he is a deserter. Leslie calls King a has-been, while King says that he gave Leslie a chance, when nobody else would. Leslie starts to maintain a log of all the damages they cause, as proof of their mission.

They reach a train station and accidentally reach the control room, when the German attendant has gone to urinate. They manage to knock him out, but then a German train arrives, waiting for the signal to pass. Leslie and King tinker with the controls and pass the train but mess up the tracks and the train ends up crashing further ahead.

They stumble across a German radar station. King says it is too risky, and Leslie is livid as King had promised that they could blow up a warship with a single grenade and now he was backing off. King explains that his bravery medal was when he was driving a general in the first world war, and the tire punctured due to shrapnel. King was changing the tire, when the car fell on him due to another explosion. King drove 10 miles in a smashed heel and that is what the medal was for.

They blow up what they take to be the main operations room, and then the entire compound unexpectedly erupts with gunfire and explosions.

They narrowly evade the Germans and escape in a boat which is later blown up by a mine; the men are picked up by the British and interrogated as possible spies. Once their identities have been established, they are returned to barracks to be court-martialed as deserters.

An aide of Churchill Major Merton (Derek Jacobi) had seen their letter, and knew of a commando raid on the radar facility which was facilitated by a diversion due to mysterious explosions in what they discover was actually the cookhouse. The aide intervenes in the court martial, establishes their presence at the enemy radar station and conveys an invitation to tea with the Prime Minister should they ever be in Whitehall.

The court nevertheless demotes Sergeant King to the rank of corporal and remands Private Cuthbertson to military prison for 28 days, lenient sentences for desertion in wartime.