A new, multilayered case for Boston-based p.i. Carlotta Carlyle (Steel Guitar, 1991, etc.), this one starting with a series of photographs of a little girl sent to her anonymously. It becomes concrete when rich, quietly distraught Emily Woodrow, the child's mother, hires her to find out more about seven-year-old Rebecca's death, of leukemia, at JHHI Hospital, headed by world-famous Dr. Jerome Muir. Carlotta enlists the help of Keith Donovan, Emily's psychiatrist, as she begins to probe, despite her misgivings about the grief-stricken mother's ability to face reality. She finds, among other things, that Tina Sukhia, Rebecca's nurse, has left the hospital and now has a lucrative but mysterious job. Adding angst is Carlotta's semi-adopted ``little sister'' Paolina, who has a new, inappropriate friend and a dangerous agenda of her own. Tina's death, apparently murder, and Emily's disappearance pile on the pressure until Carlotta finally connects the tenuous lengths that add up to a murderous scam--reaching into the upper echelons of the medical establishment. Unhackneyed dialogue, vivid characters, carefully crafted, tension-filled, never predictable plotting and the savviest, most spirited of three-dimensional heroines--Snapshot has them all. Another bull's-eye for Barnes.