The mercy seat - Martyn Waites

Once a renowned investigative journalist, since the unsolved disappearance of his 6-year-old son, Joe Donovan has lived a broken, reclusive life. He's abruptly thrust back into the real world when a teenage boy makes contact, in desperate need of his help. Jamal has in his possession something that holds a key to Donovan's past, a past that can only be unlocked by forcing him to make a terrifying journey into the present.
As long buried secrets begin to emerge and bodies pile up, Donovan finds himself caught up in a harrowing web of fear. In order to survive and uncover the disturbing truth at the heart of the dangerous world he's found himself in, he puts together a team to help him, a team of outsiders that doesn't care which side of the law it operates on. And Donovan will need their help. He and Jamal are being hunted by a death metal addicted serial killer. A killer with a 100% success rate. A killer who doesn't know the meaning of the word mercy.