All Those Broken Angels by Peter Adam Salomon

Comforted by a shadow. Haunted by the truth.

Richard Anderson was the last person to see his friend Melanie alive. She vanished when they were six, and while the police never found Melanie, a part of her remained—a living shadow that is now Richard’s closest friend.

For ten years, Richard has never questioned the shadow that keeps him company . . . until a new girl moves to town, claiming to be Melanie. Desperate to prove the girl is a fake, the shadow leads Richard to the place where her killer buried her bones. But Richard finds skeletons from several different children . . . and evidence suggesting that perhaps the shadow isn't who she says she is.