In order to make good with his former employers, a submarine captain takes a job with a shadowy backer to search the depths of the Black Sea for a submarine rumored to be loaded with gold.

Iconoclastic, take-no-prisoners cop John McClane, for the first time, finds himself on foreign soil after traveling to Moscow to help his wayward son Jack - unaware that Jack is really a highly-trained CIA operative out to stop a nuclear weapons heist. With the Russian underworld in pursuit, and battling a countdown to war, the two McClanes discover that their opposing methods make them unstoppable heroes.