Six Degrees of Separation (Book 1 - Katie Prentice, Ghost Interpreter)

Katie Prentice was a psychic. It all started when she was twelve, and she saw the murder of her best friend. Her parents believed she was schizophrenic, her doctors believed she was schizophrenic. But the truth was that she could see those ghosts who hadn't been able to cross over to the other side, and some of those ghosts were victims of crimes and were able to tell her who had killed them. Since everyone thought she was schizophrenic, she had learned that she needed to keep the ghosts private and that any clues should be given to the police anonymously. That all ended with Zoe Standish. Working together with Detective Griffin McCallister, Zoe led Katie to the fact that her death was the work of the Chronological Killer, introducing Katie to the other victims that he had killed. Zoe was twenty-four. Katie was twenty-nine. And as the numbers inched closer to Katie's age and the clues pointed to Katie being the next in the series, Griff, the ghosts and Katie worked to identify the killer before he murdered her.