In the wake of Pearl Harbor, Lieutenant Ted Lawson leaves his expectant wife Ellen to volunteer for a secret bombing mission which will take the war to the Japanese homeland. He and his crew, including co-pilot Dean Davenport, navigator Charles McClure, and gunner-mechanic David Thatcher, are among 24 North American B-25 bombers with volunteer crews assembled at Eglin Field in Florida. Led by Lieutenant Colonel Jimmy Doolittle, they embark on a low-level flight to bomb Tokyo, Yokohama, Osaka, Kobe, and Nagoya, but the mission is complicated when an enemy surface vessel discovers their convoy. The crew faces hardships, danger, and medical challenges while being escorted through Japanese-held territory, with Ellen joining them at Eglin Field.