A strongly plotted thriller about a plague-like epidemic on a space station. Superb research lifts Gerritsen to the top of the ladder as Michael Crichton and Robin Cook wave from below. Gerritsen’s tale doesn—t have the mystical touch that Stanislaw Lem would have added, though the essential mystery here is a fairly mystical monster, a multicellular microscopic organism called the Chimera. A geologist, trapped in a submersible 19,000 feet deep in the Gal†pagos Rift, ties in with an outbreak on mankind’s first internationally built space station (ISS), orbiting earth. The ISS, five years in the assembling and twice as long as a football field, is manned by an international team of scientists whose work, in part, focuses on testing the effects of weightlessness on microbes and viruses. When tested on earth, such cultures can grow only on flat slides. In space, without gravity, they grow three-dimensionally and assume unbounded shapes. Someone has hoodwinked the space doctors by having them test an absolutely unknown organism that has been lifted from bubbling thermals on the ocean floor. This creature has hideous properties that allow it to take on the DNA of any host it enters, be such lab mouse, frog, or human. Thus, any vaccine that might kill the amazing Chimera, whose DNA is part frog, part mouse, and part human, would kill the host as well. The story builds to a Liebestodt of dancing horror as fatal globules of infected blood erupt weightlessly from the dying, float about the ship, and clog the air filters. Meanwhile, the main romantic interest turns on a couple in the process of divorce, astronauts Emma Watson and Dr. Jack McCallum. Doc Gerritsen (Bloodstream, 1998, etc.), a former internist who creates chilling viral disasters, knows all the natural gates and alleys of the human bio-novel as well as she does the musculature of suspense.