Will Daisy (played by the actress June), a beautiful flaxen-haired fashion model, wind up pushing up daisies if she continues to flirt with her parents' new lodger (Ivor Novello)? After all, he looks like eyewitnesses have described "The Avenger," a Jack-the-Ripper-style serial killer of young women with golden tresses. He certainly acts "queer." Police detective Joe (Malcolm Keen), Daisy's nominal boyfriend, thinks he's a wrong 'un, but Joe is quite obviously jealous.
Joe gets assigned to the Avenger case just as Daisy and the Lodger are getting amorous for real. The Avenger claims his next victim on a night the Lodger has mysteriously stolen out of Daisy's parents' house, making Daisy's mother more than suspicious her daughter is in danger. A few nights later, Daisy and the Lodger are spooning on a bench by a lamppost when Joe comes along and assails the Lodger's impudence at moving in on his girl. Daisy haughtily breaks her almost-engagement with Joe and goes off with the Lodger. Only then does the abandoned Joe put two and two together and conclude Daisy's new beau, whom he blames for everything wrong in his world, is the Avenger.
Is he? As viewers of Alfred Hitchcock's first true thriller, a silent film from 1926, we are halfway convinced, but privileged shots of the Lodger's face that we are granted in various situations have made us feel sympathetic to him, see him as some sort of victim, not a psychotic killer. Certainly, Daisy has no doubts about him, for she resists when Joe arrests him. Taking advantage of the confusion when Daisy's mother faints at the news, the Lodger, handcuffed, bolts and escapes. Daisy meets him at their lamppost. He tells her a story of how his own sister was the Avenger's first victim. He is out to capture his sister's (and indirectly his mother's, who never recovered from the shock) killer. That's the quest that took him out of Daisy's house on that most recent fateful night. She believes him. Should we?
At the level of subtext, this is a film about Joe's patriarchal right to Daisy's hand, with her father's approval. After he puts the cuffs on the Avenger, he says, he'll be in a position, career-wise, to put a ring on her finger. Does he have a right to? Do Daisy's desires or lack thereof matter? Will her attraction for the Lodger be validated as safe and fruitful, or cost her her life and plunge her world into chaos? Hitchcock has constructed a morality play around patriarchy and, not incidentally, Christian symbolism. Notice the images Hitch places on the screen after an angry mob hunts down the handcuffed Lodger.