Late on a foggy November afternoon, a desperate young woman arrives at Baker Street, imploring Sherlock Holmes to help her. She is terrified about what may be going on inside a secretive London refuge for Russian exiles, where her sister works. Thus begins a frightening case which deeply strains both Holmes and Watson because of the dreadful consequences of failure and the mystifying nature of the forces against them. The case leads into strange territory. Into the circles of Victorian radicals and idealists, where early feminists and socialists rub shoulders with exiled foreign...