Fantastic Voyage

The United States and the Soviet Union have both developed technology that can miniaturize matter by shrinking individual atoms, but only for one hour. Scientist Dr. Jan Benes, working behind the Iron Curtain, has figured out how to make the process work indefinitely. With the help of American intelligence agents, including agent Charles Grant, he escapes to the West, but an attempted assassination leaves him comatose with a blood clot in his brain that no surgery can remove from the outside.