A science fiction film written by Harry Kleiner. Bantam Books obtained the rights for a paperback novelization based on the screenplay and approached Isaac Asimov to write it (Asimov 1980:363). Because the novelization was released six months before the movie, many people mistakenly believed Asimov's book had inspired the movie (Asimov 1980:390). According to Fred Schodt's The Astro Boy Essays, FOX also approached NBC to get the rights to an Astro Boy episode which had the same premise, but they never contacted the manga artist or credited him in the final product.
The movie inspired an animated television series, as well as a painting of the same name by Salvador Dalí.
The United States and the Soviet Union have both developed technology that allowed matter to be miniaturized using a process that shrinks individual atoms, but its value is limited because objects shrunk return to normal size after a period of time - the smaller an object is made, the quicker it reverts.
Scientist Jan Benes, working behind the Iron Curtain, has figured out how to make the shrinking process work indefinitely. With the help of the CIA, he escapes to the West, but an attempted assassination leaves him comatose, with a blood clot in his brain.
To save his life, Charles Grant (the agent who extracted him, played by Stephen Boyd), pilot Captain Bill Owens (William Redfield), Dr. Michaels (Donald Pleasence), surgeon Dr. Peter Duval (Arthur Kennedy) and his assistant Cora Peterson (Raquel Welch) board a submarine, the Proteus, which is then miniaturized and injected into Benes. The ship is reduced to one micrometre in length, giving the team only one hour to repair the clot; after that, the submarine will begin to revert to its normal size and become large enough for Benes' immune system to detect and attack.
The crew faces many obstacles on their journey. They are forced to detour through the heart (a temporary cardiac arrest must be induced to avoid destructive turbulence), the inner ear (all in the lab must remain quiet to prevent similar turbulence) and the alveoli of the lungs (where they replenish their supply of oxygen). When the surgical laser needed to destroy the clot is damaged, it becomes obvious there is a saboteur on the mission. They cannibalize their radio to repair the laser. When they finally reach the brain clot, there are only six minutes remaining to operate and then exit the body.
The traitor, Dr. Michaels, knocks Owens out and takes control of the Proteus while the rest of the crew is outside for the operation. Duval successfully removes the clot with the laser. Michaels tries to crash the sub into the clot area to kill Benes, but Grant fires the laser at the ship, causing it to veer away and crash. Michaels is trapped in the wreckage and killed when white blood cells attack and destroy the Proteus. Grant saves Owens from the ship, and they all swim desperately to one of the eyes, where they escape via a teardrop.