Conceived as a followup to Leni’s wildly successful 1927 production The Cat and the Canary (also starring La Plante), the film was produced by Universal Pictures under Carl Laemmle. Principal photography took place in Los Angeles in the summer of 1928 on sets recycled from Univeral’s The Phantom of the Opera (1925). It premiered on Christmas Day 1928 before expanding in January 1929, and was released as both a part-sound as well as a silent film; the silent version is the only known extant version. It was the final film directed by Leni before his death from blood poisoning on September 2, 1929.
Response by critics to The Last Warning varied, with many praising its performances and cinematography, though several commented on its incoherent plot, and others criticized its integration of sound, feeling it presented optimally as a silent film. In 2016, Universal Pictures selected the film for restoration, using elements from two different prints owned by the Packard Humanities Institute and the Cinémathèque Française.
In a Broadway production of a play entitled The Snare, one of the actors, John Woodford, inexplicably dies during a stage performance, and his body disappears. Few clues exist as to what caused his death, aside from several drops of liquid found that resembled chloroform. Rumors of a love triangle between Woodford and two cast members circulate as a possible motive for his death.
Five years after the theater’s closure, producer Mike Brody decides to solve the mystery by again staging the play with the remaining cast and re-enacting Woodford’s murder. During rehearsals in the abandoned theater, strange occurrences plague the cast, including ominous noises, falling scenery, and an unexplained fire. Doris, the lead actress, has her purse stolen from her dressing room by an unseen assailant; Josiah Bunce, the stage manager, reportedly receives a telegram warning him to drop out of the play, signed by John Woodford, and the theater’s new owner, Arthur McHugh, also receives a visit from Woodford’s ghost.
The production continues, and during the final rehearsal, Harvey Carleton inexplicably disappears from the stage during a blackout. Doris spots a mysterious masked figure in a theater box in addition to a man resembling John Woodford, but both disappear. Behind a picture hanging on the stage, a lever is discovered which opens a trap door, where the cast find Harvey incoherent. Arthur and Richard Quayle, another cast member, venture inside, where they discover a tunnel that leads to Doris’s dressing room.
Arthur has police officers appointed at the theater for the show’s opening the following night. During the performance, an electrical wire charged to 400 volts is discovered connected to a candlestick onstage, and Arthur lunges at Richard to prevent him from touching it during the final scene. The unseen masked assailant is discovered hiding inside a grandfather clock onstage, but he drops through a trap door in the floor just after shooting one of the police officers. The assailant scales the theater and throws a dummy resembling John Woodford onto the stage. He then begins swinging from a rope, but is brought back down by a stagehand who cuts it.
The masked assailant is discovered to be Josiah, who caused Woodford’s death via electrocution and had been behind the “hauntings” to prevent the theater from being used.
Leni, Paul [Public domain], via Wikimedia Commons