William Le Queux 
Mystery of the Green Ray 

As the novel opens four young Englishmen are enjoying a peaceful days’ relaxation punting on the river but they are all too keenly aware of the storm clouds that are gathering. It is late July 1914 and the assassination of a certain Austrian archduke has Europe poised on the brink of war. Being patriotic manly Englishmen all four friends intend to do their bit by enlisting. Before doing so young Ronald Ewart must pay a visit to Scotland to see his fiancee Myra and her father, a retired general. Ewart hopes to get in a bit of salmon fishing as well but this brief getaway proves to be anything but relaxing. Myra is also keen on fishing but disaster strikes unexpectedly — she is mysteriously struck blind! She sees a green flash and then nothing. Her father has an odd experience as well, reporting that a large rock overhanging the river seemed to be moving towards him. And then Myra’s faithful dog goes blind and as was the case with Myra it happens just as suddenly. (Goodreads)