A Western agent is sent to Communist China in order to retrieve an important agricultural enzyme. What he does not know is that there is a bomb implanted in his head; the forces behind his mission will detonate it if he fails to carry out the assignment.
Nobel Prize–winning university professor Dr. John Hathaway’s mission begins with Lt. General Shelby’s request at the U.S. embassy in London that he travel to China to visit Soong Li, a former professor of Hathaway’s who has reportedly developed an enzyme that would permit crops to grow in any kind of climate. The hesitant Hathaway is further urged to go by a phone call from the President of the United States. Hathaway is concerned about the situation, as is a close female friend he knows named Kay in London.
A transmitter is implanted in Hathaway’s skull as a tracking device. He is not informed that the device also includes an explosive element in case of emergency that can be triggered by the Americans if necessary. Neither the U.S. nor the Soviet Union wants the enzyme to remain exclusively in Chinese hands.
Shortly after his arrival in Hong Kong, Hathaway is sent to meet a beautiful young Chinese woman, Ting Ling, who introduces him to Security Chief Yin at a nightclub. When Hathaway returns to his hotel room, he finds Ting Ling waiting for him in his bed naked and enticing him to seduce her because it is her duty for the Chairman. She tries to undress him, but when he hears a noise made by an intruder he goes to investigate. He apprehends a male intruder, but Ting Ling picks up a telephone and uses it to knock Hathaway unconscious. Security Chief Yin takes Hathaway by car to meet China’s Party Chairman. They play a game of table tennis and discuss the enzyme, which the Chairman claims he intends to share with the entire world. At this moment, Lt. General Shelby, who is listening in London, considers and discusses with his seniors the possibility of detonating the explosive device in Hathaway’s head to kill the Chairman.
Hathaway is then taken by plane to be reunited with Professor Soong Li and also meets Li’s daughter, Soong Chu. No one thinks Hathaway is really spying on the Chinese regime. Soong Li, possibly betrayed by his daughter Soong Chu, is attacked by guards looking for the formula. Before he dies, Soong Li gives a book to Hathaway containing quotations from the Chairman. The professor flees with the book and a piece of microfilm, trying to reach the Soviet border before Yin’s men can capture him. He is unable to scale a fence, so Shelby elects to set off the explosive device, but Soviet border troops arrive at the last minute to help Hathaway cross safely.
Once safe, the professor discovers that the enzyme’s formula is hidden in the Chairman’s book of quotations. He gets the device removed and is taken aback when it is demonstrated to him that it contained an explosive device that could have been detonated remotely at any time. He then returns to Kay in London.