France 1880 - A bank clerk, called Lucien Cortier, is working late one night when he discovers that one of the other clerks has been murdered and the bank's money stolen. A wolf's howl marks the crime as the work of 'The Wolf', a notorious criminal who is aided by a mysterious face that appears before his victims' demise.
M. De Brisson, owner of the bank, laments his poor financial standing, made worse by this robbery. However, he is on the verge of a deal with a rich nobleman, Chevalier Del Gardo, which could reverse his dire situation.
Cecile, Brisson's daughter, discusses marriage with Lucien, but because he is penniless they both know that her father would not allow the marriage to go ahead.
Chevalier arrives and is instantly attracted to Cecile. He tells her father that he will deposit money in his bank and save his business, in return for Cecile's hand in marriage. Brisson lets Cecile decide for herself, but she tells Chevalier that she is in love with Lucien.
Meanwhile, Professor Le Blanc shows Lucien his new experimental attempt to revive dead animals, allowing their muscles to perform the actions that their brain had instigated before their death. He plans to use it on the next victim of the Wolf, so that they can reveal the identity of the murderer.
Chevalier goes to a seedy bar, The Blind Rat, and tells his henchmen to deposit a package of coins in Lucien's bank locker, as evidence of his guilt in the robbery. One of the criminals spills some wax on the package, and as Chevalier rests his hand there, the seal from his ring is imprinted on it.
An anonymous letter is sent to Brisson telling him to inspect Lucien's locker. He discovers the package and dismisses Lucien. Chevalier arrives to sign some documents, and Brisson notices that Chevalier's seal is the same as the one on the package.
Later that evening, Brisson sees the horrible face at his window, and is stabbed. Lucien, who had come to tell Cecile about his dismissal, discovers the body. Chevalier arrives and accuses Lucien of murder. Lucien challenges him to a duel.
Chevalier and Lucien meet to duel, but Chevalier's henchmen knock Lucien out and toss his body into he river. Two young lovers who have been walking nearby see what has happened, and rescue him.
Cecile receives a letter, apparently from Lucien, telling her to meet him in The Blind Rat. She arrives and is sent to an upstairs room, only to discover that it is Chevalier who is waiting for her. He attempts to rape her, but is distracted by the arrival downstairs of Lucien, disguised as the recently escaped convict, Jacques Renaud.
Chevalier goes downstairs and reveals Lucien to be a fraud, just as the police arrive. Lucien runs upstairs and throws a lamp to the floor, setting fire to the building and distracting the police while he escapes with Cecile.
Cecile arrives at the police headquarters a few days later, and tells them and Chevalier to meet her at Professor Le Blanc's house, where he will use his experiments to reveal the identity of the murderer. However, before they arrive, Le Blanc sees the face and Chevalier stabs him.
Lucien performs the experiment, and the Professor's hand writes down his murderer's name - Chevalier. Chevalier confesses to being the Wolf, before jumping out of the window into the river below. It is revealed that it was not the Professor's body under the sheet, but one of Lucien's friends who was pretending in order to trap Chevalier.
Chevalier arrives back at his house, and goes into the cellar to speak to his deformed foster brother, who is in fact the 'face'. He is in a cage that is lowered down to the edge of a door opening out onto the river.
The police arrive and distract Chevalier, allowing his brother to reach out from the cage and grab his throat, pulling them both into the river's murky depths. Lucien and Cecile embrace, and the Wolf's reign of terror is over.
