Take five people, put them in a submarine and shrink the whole kit and caboodle to the approximate size of a molecule. Inject said sub into the bloodstream and do not shake. Thus you have a fantastic voyage as the tiny ship and crew set out to destroy a bloodclot that is damaging the brain of the world's most valuable scientist. And, as if white corpuscles were not enough, there is also skullduggery aboard ship. Biology buffs in particular will be swept along and for the fan in general, it's blood curdling. Asimov is a shot in the arm.