Murder in the Hispanic section of San Francisco's Mission neighborhood, investigated by Latino homicide-cop David Cruz--in a somber, sturdy, slightly overwrought debut. The victim is young Gloria Soto, a refugee from El Salvador, found on the street, trussed and executed in ""death squad"" fashion. The prime suspect: Eric Hernandez, who has always manically courted Gloria--despite the fact his family (guerrillas) and hers (landowners) have been on opposite sides of the Salvadoran bloodbath: Gloria's uncle is sure that this unhappy suitor killed not only Gloria but also (back in El Salvador) her father and brother. But, while hunting for Hernandez, brooding cop Cruz--egged on by the fugitive's passionate sister--begins to look elsewhere for the real villain. Gloria's new beau, for instance, is a fat thug involved in the smuggling-in of illegal aliens. There also seems to be a secret rightwing death-squad at work in the Mission. And, after another young woman (Cruz's favorite social worker) is killed, the layers of vendetta-motivation are fully revealed. . .but not in time to save the Romeo in this Romeo-and-Juliet scenario. First-novelist Lantigua overdoes Cruz's interior angst; by strained coincidence, it's the cop's estranged wife (she finds him cold) who's been hiding Hemandez. Otherwise, however, this is a darkly effective police-procedural--only serviceably plotted, but strong on neighborhood atmosphere and the ripple-effects of Central American violence.