Vanish — Tess Gerritsen

A nameless woman appears to be just another body at the morgue--until Boston medical examiner Maura Isles sees the corpse open its eyes. The now-frantic Jane Doe is rushed to the hospital, where with cool precision she shoots a security guard and seizes hostages, one of whom is pregnant homicide detective Jane Rizzoli. As the tense hours tick by, Maura joins forces with Jane's husband, FBI agent Gabriel Dean, to track down the killer's identity. But this case goes far deeper than just an ordinary hostage crisis, and Jane, trapped with the armed madwoman, is the only one who holds the key to the mystery.