While escorting a supply convoy to an off base communications site north of Bagram Airbase Afghanistan, Master Sergeant George Mavrakis and his team are ambushed by the Taliban. Running for their lives with the few survivors of the ambush they manage to flee to an underground mine, but are trapped inside when a Taliban suicide bomber blows himself up in the entrance, sealing them inside. Traveling deeper into the mine they discover an underground base left there by the Soviets. While exploring the base they find a control room filled with computers and equipment which activated after generator power was restored and a countdown is automatically started.
The arrival of George and his troops from the future have drastically altered the timeline. The Ottoman Sultan Mehmet II will soon put the city of Constantinople under siege with over 80,000 troops and 60 huge guns that can tear down the city's walls. In the American's past time line, the Ottomans do capture the city and the emperor is killed in battle. It will be race against time to assist the Byzantines in building up their technical and military capabilities with the skills and knowledge, they brought back from the future, to stop the Ottomans. If they are unsuccessful the future is very bleak for George and his team, whom are lost in time
