A floater, his optometrist says. Nothing to worry about. Microscopic bits of protein adrift in the humor that cast shadows on the retina. But Dempsey's worried. For one thing, instead of dispersing, the floater continues to grow, occluding his vision and causing disturbing hallucinations. For another, his partner, Pinero, is behaving strangely and there's the suggestion that the floater may not be a harmless opthamological incident but an emblem that signals a peculiar form of vengeance and the imminence of a voodoo god. As he tries to determine what is happening, Dempsey's investigation leads him from rave culture to santeria ceremonies in storefront temples and, ultimately, to a circumstance that may have cosmic implications and a truth that lies hidden in the deepest sub-basements of his own mind.