Good vampires vs. evil vampires on the ante-bellum Mississippi--with a fat, tough old steamboat captain perilously caught in between. This reluctant hero is Abner Marsh, once-prosperous owner of an ill-fated steamboat fleet--who can't resist an offer from pale stranger Joshua York in 1857 St. Louis: York will finance the building of a luxurious new steamboat for Marsh to captain . . . but there are to be no-questions-asked about York's eccentric doings on-board. And eccentric they are: York never appears in daylight aboard the Fevre Dream; he has an odd gaggle of similarly inclined traveling-companions; he orders the boat stopped in weird spots along the way; and . . . what about those bloodstains or that ledger-book filled with newspaper reports of murders Well, vampire-readers will catch on promptly--especially since sf award-winner Martin, in alternating chapters, offers the grisly goings-on at the Louisiana bayou manse of Damon Julian, a "bloodmaster" of the most vile sort. But it takes Capt. Marsh a good while to figure out that York is indeed a vampire. (York at first claims that he's just hunting vampires; he even appears in daylight, risking death to prove his humanity.) And when the secret is bared at last, York tells an eventually sympathetic Marsh the whole truth--including the fact that youngish vampire York (b. 1785) has, after much struggling, concocted a blood-substitute for the accursed vampire species: "I conquered the red thirst!" York's mission, then: to locate the world's vampires, to give them all the elixir, and to make vampire/human brotherhood possible. Rival bloodmaster Julian, however, is quite happy to keep his followers going with cannibalism and bloodsucking. So, when the Fevre Dream reaches New Orleans, there'll begin a series of violent showdowns--as Julian takes over the boat and imprisons York & Co., surviving assorted attacks by Marsh (who's forced to flee). And finally, after Marsh revs up his old, creaky steamboat to search for the Fevre Dream, the good vampire and his now-devoted pal will undergo grim ordeals before vanquishing kinky, sadistic Julian. Despite a few super-gory moments and a slightly too-leisurely pace--the best vampire novel since Suzy McKee Charnas' The Vampire Tapestry: generally understated, firmly grounded in the Twain-worthy steamboat setting, abundantly creepy . . . and modestly resonant in the portrayal of inter-species camaraderie.