Trouble at the Rockland (Mass.) Zoo: a mamba bites receptionist Joanne Nordstrom (who dies because someone's sabotaged the fridge that keeps the antitoxin cold); endangered-list red wolves savage manager Donald Stewart, who has taken too close an interest in the zoo's finances--now being handled by Alex Cristos (whose ""mouth formed a cool, saccharine smile that didn't impact the rest of his face"") and by Edward Hargreve, son of late director H.L. Hargreve--and there's growing evidence that H.L., apparently killed by Kenyan poachers, was professionally hit, maybe by the same guy who's leaving scheming Edward notes claiming that ""the lion's share is mine."" Three more Homo sapiens will get put down before new vet Carlson Maclntyre can win a reprieve for those wolves by fingering the real killer--but since, as in most zoo mysteries, the animals are more varied and interesting than the humans on display, there's no cause for alarm. First-novelist Tate, teaming up with zookeeper Hanna (Monkeys on the Interstate, 1989), has succeeded in producing a genre piece that, like its intrepid protagonist, is ""tired down to [its] very bone marrow.