Sequel to The Mind Pool (not reviewed), from the scientist-author of Starfire (1999), etc. Through the instantaneous transport devices known as Links, humans have investigated parts of the galaxy, encountering three alien species who coexist in a loose association: the tall, thin, morphing Pipe-Rilla; the Tinkers, each an association with thousands of butterfly-like components; and the Angels, weird symbioses half-plant, half-intelligent crystal. These pacifist species decided that humans were too homicidal to let loose, and closed all the extrasolar Links against them. But now the aliens need human help. After the appearance of a new Link in the Geyser Swirl, two investigating expeditions vanished without trace; a third, human vessel, also disappeared. So the Angels call upon Chan Dalton, with whom they worked before, to lead a rescue attempt—nonviolently, of course. Dalton pulls together his old team, consisting of magicians, con men, weapons experts, animal talkers, etc. (some of whom have unfinished business to transact with Dalton). Aboard a disarmed space cruiser, and led by old general Dag Korin, they proceed through the Link—only to arrive, not in the Geyser Swirl, but instead underwater, on a planet awash in heavy water, in another universe altogether! Worse still, there are hostile aliens in the offing.
Doesn’t quite end on a cliffhanger, though leaving plenty of loose ends to be raveled up in the next installment: an overlong but agreeably inventive, semicomic potboiler.