The Face at the Window is a melodramatic detective play written by F. Brooke Warren and first produced in 1897.
[1] Set in Paris, the play's villain is a serial killer named Le Loup, who precedes his killings with a loud wolf-howl.
He is pursued by the master detective Paul Gouffet.
In an iconic scene, Gouffet causes a dead victim to complete the act of writing his murderer's name by passing an electric current through the arm muscles.
The 1897 play gave rise to a succession of film versions.