Director Fuller used a White House announcement of a nuclear bomb of foreign origin that had been exploded outside the US as the basis for this film. An announcer comes on at the beginning of the film saying that the movie is the story behind the mysterious explosion. Francen is the leader
of a group of scientists worried about the government's inability to handle the threat of nuclear war. They hire Widmark to command a submarine to search for Communist atomic arsenals in the North Pacific. Arriving at their destination, the crew and scientists find that the Reds plan to drop an
A-bomb from an American B-29 on North Korea and lay the blame on the US. Widmark and h...