The Phantom Archer, by Edmund Glasby (epub/Kindle)

Over the course of the late summer and early autumn, six horrible deaths had occurred. Five men and one woman. The evidence suggested that all had died during the hours of darkness and, more puzzling, none of them displayed any signs of external physical damage. No bruising. No lacerations. No stab marks. And yet, the X-rays and the post-mortems had revealed incredible evidence of extensive internal trauma; perforated scapulae and hip bones, shattered femurs and ulnas, ruptured livers, severe lung punctures and abdominal damage. In three instances there were “bullet-like” injuries to the skull.

It's up to Detective Inspector Andrew McGovern to investigate—no matter which weird, uncanny direction to clues go!