In the early 20th century, British archaeologists embark on a perilous journey to uncover the tomb of Genghis Khan. They seek not just historical artifacts but also the legendary sword and mask believed to possess immense power. Sir Lionel Barton leads the expedition, determined to ensure these potent relics do not fall into the wrong hands. However, their mission attracts the attention of the malevolent Dr. Fu Manchu, a Chinese mastermind with ambitions of world domination. Fu Manchu kidnaps Sir Lionel, intending to extract the location of the tomb through torture, while Sir Lionel's colleagues, Nayland Smith and Dr. Petrie, scramble to rescue him and safeguard the relics.

As Fu Manchu employs a combination of dark rituals and advanced technology to intimidate and subdue his adversaries, the safety of the world hangs in the balance. The British team's efforts to thwart Fu Manchu are met with various obstacles, including deception, betrayal, and lethal traps set by Fu Manchu's loyal daughter, Fah Lo See. The archaeologists must use their wits, courage, and resilience to navigate the dangers and prevent the immense powers of Genghis Khan’s mask and sword from being exploited by the devious villain. The outcome of their dire struggle will determine the fate of global peace and the direction of the future.