Tess Gerritsen left a successful practice as an internist to raise her children and concentrate on her writing. She gained nationwide acclaim for her first novel of medical suspense, the New York Times bestseller Harvest. She is also the author of the bestsellers Life Support, Bloodstream, and Gravity, as well as The Surgeon, The Apprentice, and The Sinner. Tess Gerritsen lives in Maine.

Boston medical examiner Dr. Maura Isles is shocked to discover that the murdered woman looks exactly like her. For Maura, an only child, a DNA test confirms the startling fact: the mysterious doppelgänger is in fact her twin sister. Now an already bizarre homicide investigation becomes a disturbing excursion into a past full of dark secrets and twisted truths. It is a journey that leads Maura to the mother she never knew—an icy and cunning woman who gave Maura life . . . and who just might have a plan to take it away.