The baffling murder of a famed Parisian artist in his locked and guarded studio takes the tenacious Detective Inspector LeBrock of Scotland Yard and his faithful adjunct, Detective Ratzi, into the cutthroat Grandville art scene to track the mysterious assassin. As the body count mounts and events spiral out of control, the investigation points to Toad Hall, where a cabal of industrialists and fat cats plot the overthrow of the French State . . . by use of steam-driven automaton soldiers!