American scientist John Hathaway (Gregory Peck) is sent to Communist China to steal a coveted formula from an eminent researcher (Keye Luke) -- and has no idea that his own brain is a ticking time bomb. The awful truth is that the same microtransmitter the CIA implanted in Dr. Hathaway's skull to record everything he sees and hears is also a lethal weapon that's designed to detonate if he blows his mission.