Forty Signs of Rain Kim Stanley Robinson (Bantam, $25)
Tibetan Buddhists and a motley crew of scientists are caught in an environmental disaster. LOGLINE Kundun meets The Day After Tomorrow. SOURCE OF ANGST ''The ability to end suffering and want as well as ecological collapse is right here...and yet [the National Science Foundation] continues to dole out its little grants, fiddling while Rome burns!!!'' KEY CONCEPTS Genetic modification, spiritual logic. LOWDOWN A realistic look at scientists, but the dry story line offers a creaky start to a planned trilogy. B-
Ringworld's Children Larry Niven (Tor, $24.95)
Interspecies war threatens the deep-space ecosystem Ringworld; only Louis Wu (from the last trilogy) can restore stability. LOGLINE Star Trek: The Motion Picture meets IMAX Space Station 3D. SOURCE OF ANGST ''These Ball World species covet the technology that made the Ring-world.... They want the knowledge, and to keep it from each other.'' KEY CONCEPTS Anti-matter, quantum hyperdrives. LOWDOWN Newbies to Known Space may feel lost at first, but Niven's world has an inner logic grounded in science. B
Heaven Ian Stewart and Jack Cohen (Warner, $24.95)
Evangelists from the Cosmic Unity faith attempt to convert creatures of the planet No-Moon, until one missionary learns the religion's deepest secret. LOGLINE Finding Nemo meets The Order. SOURCE OF ANGST An aquatic species threatened by Cosmic Unity seeks refuge on an even more dangerous planet. KEY CONCEPTS Galactic cults, gene hacking. LOWDOWN The herds of lavender light, telepathic ponds, and charnel houses of hell make for an edifying, albeit jumbled, read. C
Thinner Than Thou Kit Reed (Tor, $24.95)
When fitness becomes a national religion, the anorexic and obese join forces to fight Reverend Earl's binge-and-purge empire. LOGLINE Super Size Me meets Soylent Green. SOURCE OF ANGST ''See, the metabolically challenged, which is most of us, fix on the next meal like alcoholics focused on the next drink.'' KEY CONCEPTS Corporate evangelism, body modification. LOWDOWN Despite Thinner's feisty, plus-size characters, the deeper message is a bit malnourished.