Boston's redheaded, six-foot ex-cop Carlotta Carlyle, now a private eye and part-time cabbie (The Snake Tattoo, etc.), faces a daunting puzzle after a visit from a frightened Spanish-speaking woman who says her name is Manuela Estafan--which is the name of a murder victim found in a local park. Manuela wants Carlotta to retrieve the green card that identified the corpse--the card that allows aliens to work and apply for citizenship--because, she says, it's rightfully hers. She then drops $500 on Carlotta's desk and disappears. Working past connections--as well as an old friendship with the police department's Lieutenant Joseph Mooney--Carlotta is gradually drawn into a case that's beginning to look like the work of a serial killer. There are other aspects too--some of them touching the lives of Carlotta's ten-year-old friend and protÃ‰gÃ‰e Paolina and her testy, harried mother Marta. Meanwhile, agents from Immigration and Naturalization are skulking the edges, one of them a handsome hunk from Texas who almost makes Carlotta forget lover Sam Gianelli, who's been too long absent in Italy. Four women are dead before the tense hostage confrontation in the heart of Boston's subway system wraps it all up, ending another winner for author Barnes and her indomitable but always human heroine. A sturdy plot, believable if sometimes bizarre characters, and an unflagging pace make this one a must.