The game begins in Britain, 1940, where several American pilots volunteer with the Royal Air Force to take part in the ongoing war against Germany. One of them, the player, known as the Captain, is training alongside squad mate Joe, when they suddenly find a fellow pilot named Tom being attacked by German fighters. The Captain rescues Tom, who turns out to be Joe's brother-in-law.
The Captain, along with his squadron consisting of Tom, Frank and Joe, end up fighting in battles against the Germans, first by helping defend Allied forces at Dunkirk and then repelling German attacks on Britain, including a battle over London, where they encounter a German air ace. The squad is then sent to North Africa, where, after the Captain provides a reconnaissance mission on German positions, he and his squadron fight fiercely to help cover British forces assaulting German lines in a vicious battle in the Libyan desert. After this, the squadron is sent back to the United States to help train American pilots.
As they are stationed in Hawaii, the Japanese Imperial Navy launches a surprise attack on Pearl Harbor, and the infuriated squadron assists in angrily repelling the attack. With the United States now fully committed in the war against Japan, the squadron is sent on several missions against Japanese forces in the Pacific. First, they embark on a mission to destroy a Japanese convoy, including a carrier, in the Coral Sea and then they fight in the Battle of Midway, defending an airfield from Japanese air attacks and then covering bombers from swarms of A6M Zeroes as they destroy a large Japanese fleet. After fending off Japanese amphibious attacks and destroying a Japanese battleship in the fighting for Guadalcanal, the squadron is sent to assist US landings at New Georgia, defending them from enemy planes and destroying Japanese tanks and bunkers. Finally, the squadron is sent to assault the main Japanese South Pacific base of Rabaul, covering US bombers in destroying an airfield before the squadron then decimates the rest of the Japanese base.