The war was all but over-but there was still one battle the United States had to fight.

In the last year of the Vietnam conflict, even as American troops were leaving for home, there were still those fighting for their lives: prisoners of war being held in the Communist north. This is the incredible true story of a rescue mission that was classified Top Secret for years-Operation Thunderhead.

The Navy SEALs and the Underwater Demolition Teams who took part knew that if they were captured, they would be killed, tortured, or simply disappear forever. They went in anyway.

Here, the details of Operation Thunderhead are revealed-the mission, the materials, and the men who put their lives on the line to save their brothers in arms.