After an extensive archaeological expedition in the Mongolian desert, Dr. John Benton is in San Francisco to present the team’s findings to his colleagues. The recovered material reveals the long-sought tomb of an Emperor of the Ming dynasty, and inside the tomb the team uncovers a scroll that speaks of a secret Temple of Eternal Fire. This temple is believed to guard a previously unknown oil reserve, a treasure of enormous potential value for the Chinese people if it could be located and tapped.
During the opening of the tomb, a violent hurricane, foreseen by an ancient curse guarding the site, claims the life of Mason, Benton's co-pilot. The storm seems almost supernatural, as if the tomb itself is testing the living. Back at Benton's office, just as he is about to reveal the scroll’s contents during a lecture, he begins to choke and suffocate, and he dies in front of surprised colleagues.
Following Benton's death, the scroll goes missing from a safe in his office. Benton's secretary, Win Len, maintains she has no knowledge of its whereabouts. Benton's student, James Lee Wong, takes up the investigation into his professor’s death and quickly connects the dots to a poisoning reference that matches an oriental vegetable toxin. In his search, he discovers a pitcher and a glass cup containing traces of the poison, suggesting foul play rather than an accident or suicide.
Meanwhile, another expedition member, camera operator Charles Fraser, is attacked in his home and left injured. James and Street—Street, a police captain who provides early assistance—find Win Len bound and gagged at Fraser’s residence, making it clear that the danger reaches beyond Benton's death. They begin to realize that Mason faked his own death at the tomb and that Benton's loyal butler, Jonas, is involved in a plan to seize all artifacts from the tomb.
The investigation pushes outward to a waterfront hideout where Mason and Jonas are hiding after the attack. Mason makes his escape through a secret door, and James and Street uncover an artifact connected to the tomb. They also discover Jonas’s dead body in a coffin—poisoned and stabbed—confirming the depth of the plot to control the tomb’s riches.
To flush out the killer, James and Street publish a newspaper report claiming that Mason is ill with yellow fever and hospitalized. The ruse lures the killer into the hospital, where James wears a wire and impersonates Mason to draw him out. Mason himself arrives, along with Fraser, leading to a tense confrontation that is interrupted by Street and the police before it can explode into violence.
The investigation reveals that Fraser had been collaborating with Mason but tried to double-cross him by breaking into Benton's safe to steal the scroll. Fraser also killed Benton to keep the secret of the oil reserve to himself, and he killed Jonas as part of the same scheme. Though the original scroll is destroyed, a photograph of it survives, offering a clue rather than a cure for the mystery. After Fraser’s arrest, the photograph is handed over to the Chinese government so that they can work with what remains to locate the elusive oil reserve.
