The Third Twin - Ken Follett

In the course of her work, beautiful scientist Jeannie Ferrami stumbles across a baffling mystery: Steve and Dan appear to be identical twins, but were born on different days, to different mothers. A law student and a convicted murderer they seem a world apart, but when Steve is accused of a terrible crime, Jeannie must question just how different they really are. As she begins to fall in love with Steve, Jeannie finds more than her professional future threatened. Her life is also now at risk! Together Steve and Jeannie will investigate the mystery, incover all the secrets But some secrets were meant to be left alone