Time Out says
Very nearly a corking sci-fi lark, kicking off from the premise that when a top scientist defecting to the West suffers brain damage in an assassination attempt, the only answer is to inject a miniaturised submarine and medical team through his bloodstream to deal with the clot on his brain. The voyage through the fantastic landscapes of the body is brilliantly imagined, with the heart a cavernous vault, tidal waves menacing the canals of the inner ear (caused when a nurse drops an instrument in the operating theatre), cyclonic winds tossing the sub helplessly about as the lungs are reached. The script, alas, is pretty basic, expending half its energies on delivering a gee-whiz medical lecture, the other on whipping up suspense around the mysterious saboteur who lurks aboard (and is so sweatily shifty-eyed that there isn't much mystery). An opportunity missed, therefore - especially as the imaginative sets are slightly tackily realised - but fun all the same.