Obsession - Jonathan Kellerman

Patty Bigelow thought she'd finally figured life out. Then her wayward sister Leila abandons her child, Tanya, on her doorstep. The aunt and troubled niece slowly learn to live together, with the help of Dr Alex Delaware's counselling.

Now, fifteen years later, Tanya is back in Alex's office, a self-possessed Harvard student, about to enter graduate school in clinical psychology. Patty - the only real mother she's ever known - has died and left Tanya with a chilling legacy: a deathbed confession that her aunt murdered a man years earlier.

Tanya has tried to let go of the confession. But it soon becomes clear that nothing short of finding out the truth will do. And she needs Alex's help . . .