When he gets to re-meet Mary Emmett she asks if he could possibly find out for her. He remembers John Emmett fondly because of a great kindness when he was a young teen. He remembers Mary Emmett from that time, and marvels that she is still the attractive woman he remembers from his teens. He agrees to make a few enquiries and in modern parlance, that's when the can of worms is opened. What he uncovers is a dreadful perversion of justice, much cruelty and a great deal of revenge.
There are descriptions of some of the horrors of war, but not such much the death and destruction caused by the battlefield, but a good deal about those soldiers "shot at dawn" - meaning that they were sentenced to death because of extreme cowardice or desertion. In fact over 300 servicemen were executed in WW1, although over 3,000 death sentences were issued, most were commuted. Only three officers suffered the same fate. This was a book I couldn't put down, and Speller has a lovely style. Some good read herrings make the final reveal a bit of a gasper, and it is then that all the loose ends are knitted together - including a rather shocking epilogue which must not be ignored. And does Laurence get the girl? for that is the side story in this book. He is attracted, but does not think it seemly at first. She seems to like him but there are mysteries about Mary. You'll find out.