Battle of Okinawa, April, 1945. Crouched behind the trigger of an anti-aircraft gun on the destroyer USS Callaghan you wait, scanning the sky. Black dots on the horizon... Japanese Zero fighter planes... lots of them. There's just one thing between them and the lumbering aircraft carriers of the Allied Fleet: you. Can you do this? How does it feel? Cold as the bottom of Pearl Harbor is how it feels. You bare your teeth, but nobody would call it a smile. The time has come. It's Zero Hour.