When the body of social worker Kera Jacobsen shows up on Chief New York City Medical Examiner Laurie Montgomery's autopsy table, it appears she was the victim of a drug overdose. But for Laurie and her new pathology resident, the brilliant Dr. Aria Nichols, little things aren't adding up. Kera's family and friends swear she never touched drugs. Administrators from the hospital where Kera worked insist the case be shrouded in silence. And although Kera was ten weeks pregnant, nobody knows who the father was--or what he might now about Kera's final moments alive.

With Laurie temporarily sidelined by a medical emergency, impulsive Aria turns to a controversial new technique: collaborating with experts at a start-up ancestry website to trace the fetus's DNA in the hopes of identifying the mystery father. But when Kera's fellow social worker is murdered, it becomes clear that someone doesn't want Kera's secrets to come to light . . . and if Aria gets any nearer to the truth, she and Laurie might find themselves a killer's next targets.