Amiable if overlong hardcover introduction to Aristotle ``Soc'' Socarides, a Cape Cod fisherman/sleuth of Greek heritage. Soc is hired to work undercover at the Oceanus Aquatic Park. His mission? To prove that Rocky, the killer whale, didn't intentionally kill his sadistic trainer Eddie Byron. Matters escalate when: the fired p.r. director of Oceanus is also killed; Soc is attacked in the shark tank; an environmentalist group with a penchant for terrorism not only pickets Oceanus but also infiltrates its staff; and Soc's budding romance with Sally, head dolphin-trainer, is threatened by a jealous co-worker. Plus: Dan Austin, the aquarium manager, is less than forthcoming about recent staff-replacements and a possible buyout by a group of Japanese businessmen. With the help of a Native American government spook, Soc uncovers all the aquarium's secrets--including the very fishy way it stocks its tanks. Much repetitive moralizing about ``whale jails,'' etc., and some data on training dolphins and whales, but nothing much new or compelling here. The relaxed, low-key narration is its best asset, making for an easy read.