In the London fog, two men bump into each other one night. They are immediately unnerved by their exact resemblance to each other. Jack Chilcote MP is a rising political star and John Loder a man with a thwarted ambition. The plan they jointly hatch leads to a story of high tension both politically and personally. The book has been turned into a play and four films over the years. The authoress sadly died in 1911 at the age of 36.