In 1943, after defeating Rommel's forces in North Africa, the Allies are setting their sights on Southern Europe. As a prerequisite of a probable invasion of Europe through Italy, the Allies must place observers on various uninhabited islands in the Adriatic Sea to report on eventual German troop movements and German Navy deployments. The British select a small uninhabited island off the coast of Albania to dispatch a team of Army observers. The team of four men is comprised of Lieutenant Brown, Sergeant Bolter, private Finch and private Ackroyd. This small task-force is code-named 'Force X' and their secret operation is code-named 'Plantagenet'. Dropped on the island in a small dinghy by a British submarine, the group sets-up camp, prepares defensive positions and tunes-up the wireless transmitter. Later, they set out to recon the entire island to make sure there are no enemies on it. Despite assurances from their HQ that no German is on the island, the four-man British team discovers an old Byzantine monastery. Inside it there are German soldiers, of course. However, it's a Mexican stand-off situation because the German team is also comprised of four men, Captain Krisling, sergeant Meister, the cook Schmidt and private Voss, an ex-archaeology professor. With the wireless transmitter not functioning, the British cannot contact their HQ. They are tired, hungry and thirsty. They decide to attempt a night attack on the monastery where the Germans are sheltered. Inside the monastery, the Germans, who are well supplied with ammunition, food and water, offer the British a truce. It's suggested that they all should live in a peaceful co-existence until picked-up by their respective submarines. Initially, the British refuse to co-operate, due to their pride and hatred of the enemy but later re-consider the German offer when they notice the Germans have plenty of provisions, including wine, sausages, bakery products, an excellent cook and even a gramophone with music records. They agree to jointly rule the island with the German team that has occupied it for several months before the British arrival. They all agree to take turns cooking, pulling watch-duty and doing menial tasks such as cleaning. The German Captain and the British Lieutenant agree to take turns being the joint camp commandant. This ideal arrangement works well in the beginning. One British private and one German private even share the hobby of archaeology and they go digging for Pterodactyl fossils together. The other two 'enemy' privates share a passion for cooking and they concoct delicious recipes for their mates. The two officers drink wine, play chess and debate worldly matters. Soon, they're all friends and on first-name basis with one another. The sergeants, are the only exception since they are belligerent war lovers who believe there should be no fraternizing among enemies. Every day, the two sergeants clean their weapons while giving ugly stares to one other or gnarling unfriendly remarks to each other while claiming to be friendly only because of the orders to do so. Eventually, tired of being forced by their officers to be polite, the two sergeants decide to steal the dinghy and row it to the continent where they could rejoin the war. The others seem happy with their peaceful life together, that is until a beautiful shipwrecked woman is washed up on their beach. Then, the gallantry commences. They all seem determined to woo Elsa, the beautiful stranger, who doesn't speak either English or German but speaks a bit of Italian, which one of the British soldiers also speaks. These soldiers, who haven't seen a woman in 3 years of war, suddenly compete against one another for this attractive newcomer's affections. This competition leads to open conflict and to the realization that they are, after all, enemies and their countries are at war.