This is the fifth novel from the master of “surf noir,” a niche genre to be sure but one Numm, a former surfer who lives in Southern California, uses not only to tell crackling thrillers, but also to explore depths of character and provocative issues. This one is about Sam Fahey, a former surfer-turned-dope smuggler trying to go straight as a worm farmer, of all things. Fahey’s glory days riding the huge waves on the Tijuana Straits, on the California-Mexico border, are long gone but far from forgotten. Into his dreary life in the Tijuana River Valley comes Magdalena, who’s fleeing some thugs who tried to kill her, apparently because of her work exposing the environmental crimes of Tijuana’s maquiladoras, or foreign-owned factories. And then there’s Armando, a man whose mind is so confused and distorted by drugs and pollutants and personal tragedies that he’s marked her for death. As Magdalena tries to solve the mystery of who’s trying to kill her, Fahey slowly emerges from isolation and into connection with her—and so is put to a final test when the beast comes to call.