When her brother is killed, brilliant marine architect Hannah Bryson must discover the volatile mystery behind a decommissioned Soviet submarine, Silent Thunder, that was recently purchased by the U.S. government for use as a maritime museum. Though the U.S. government tries to warn Hannah away, she'll stop at nothing to find the ruthless mastermind behind her brother's death. Even if it means joining forces with a mysterious man who may be even more dangerous than the enemy she has sworn to bring down.