The Ascending — T.M. Wright

Ryerson Biergarten is always willing to offer his psychic services to the forces of law and order. But when he tries to help the police find a serial killer who is stalking victims in one of the tallest buildings in the world, he is met with distrust and suspicion.

As Ryerson follows the psychic path of the killer, joined only by a budding psychic who wants to be his Watson, he faces obstacles at every step - and the body count keeps rising.

Ryerson knows well the mysterious border between life and death, but this time he needs the earthly help the police refuse to give. This time he fears he is dealing with an evil beyond his powers: possession.