1896. A new client at Baker Street claims he's being threatened via the new art of the moving image...

Eadweard Muybridge, pioneer of motion picture projection, believes his life is in danger. Twice he has been almost run down in the street by the same mysterious carriage, and moreover, disturbing alterations have been made to his lecture slides. These are closely guarded, yet just before each lecture an unknown hand has defaced images depicting Muybridge himself, which he has discovered, to his horror, only as he projects them to his audience. As Holmes and Watson investigate, a bewildering trail of clues only deepens the mystery, and meanwhile, newspaper speculation reaches fever pitch. The great detective's reputation is on the line, and may be ruined for good unless he can pick apart a mystery centred the capturing, for the first time, of figures in motion, and the wonders of the new cinematograph.