Henry Wade 
Constable Guard Thyself! [EPUB ebook] 

Two threats from a newly released convict—a poacher framed on a murder charge—put Captain Scole, Chief Constable of Brodshire, on his guard. Special men are assigned to protect him. But four days later, Captain Scole is found shot through the head at his desk in Police Headquarters.

A full week later, young Inspector Poole of Scotland Yard is called in to follow a cold trail in the face of open hostility from the local police. And the further he explores the murder, the more baffling it becomes. Could Scole’s First World War past be catching up with him—or something much closer to home?