At Some Disputed Barricade (World War I Series, Novel 4)

It's July 1917, and as the sun sets over No-man's-land so Joseph Reavley's heart sinks with it. As chaplain he must keep up the men's morale, but as rumours of mutiny grow stronger he is losing any chance of getting through to them. After the death
of an officer, twelve soldiers are arrested, and it falls to Joseph to uncover the truth about their involvement.
Joseph's brother Matthew, of the S.I.S, is also in pursuit of the truth, whilst struggling to come to terms with his part in the Peacemaker's death. Approached by a Junior Cabinet Minister who is being blackmailed, Matthew learns of a plot to destroy the only men who can bring about lasting peace. As he embarks on an investigation Matthew knows his own life is in danger but thinks it a small price to pay to secure the future of millions of people.