Hitchcock's first thriller. It starts great, with a montage of the hysteria sweeping London in reaction to a serial killer who murders a different blonde woman every tuesday night. The middle section deals with the lodger, played by Ivor Novello, a stranger who arrives at a boarding house and arouses his landlady's suspicion. This section is a little overdone, Hitchcock overplaying the creepy stranger card, but it's still a decent film, and certainly fascinating for any fan of the director. Many of his trademarks pop up in this film: innocent man charged with murder, crime associated with sex, blondes versus brunettes, handcuffs, stairwells.
On a sidenote, just last night I watched the latest Doctor Who episode, also called The Lodger, and also involving a mysterious stranger who lives upstairs. It was not really the same story as the Hitchcock film but it was another strong episode in this season of Doctor Who.