Fantastic Voyage - Isaac Asimov

A fabulous adventure into the last frontier of man!Attention! This is the last message you will receive until your mission is completed. You have sixty minutes once miniaturization is complete. You must be out of Benes’ body before then. If not, you will return to normal size and kill Benes regardless of the success of the surgery.Four men and one woman reduced to a microscopic fraction of their original size, boarding a miniaturized atomic sub and being injected into a dying man''s carotid artery. Passing through the heart, entering the inner ear where even the slightest sound would destroy them, battling relentlessly into the cranium.Their objective . . . to reach a blood clot and destroy it with the piercing rays of a laser. At stake . . . the fate of the entire world.