Sea Fog, by J.S. Fletcher (epub/Kindle)
Tom Crowe, sheltering for the night in a disused windmill on a Sussex down overlooking the sea, witnesses a brutal murder, which he is powerless to prevent. A series of extraordinary and baffling mysteries follow, all springing from a dark and tragic crime committed forty years before.
Trawlerson, a mysterious seaman seeking for treasure; Chissick, an ex-convict; Preece, a village policeman; Halkin, the subtle and sly; are all mixed up in the plot. And Parkapple of the C.I.D., a man of fame and skill, handles the case.