Werewolf of London is about a scientist from London who travels to a remote location while looking for a rare flower so he can grow it in his greenhouse back at his home. He finds the flower he has been looking for but is bitten by a werewolf when he finds it. When he gets back home he shows his entire collection to some of the upper class people but realizes later on that the bite from the werewolf is also turning him into a werewolf as well.
He tries to cure himself with the flower but a wolf continues to kill people in London. It isn’t until the end of the movie that we realize the actual one responsible for most of the murders was the guy who bit the scientist during his trip and is played by the first Charlie Chan actor, Warner Oland, around the same time he was in his Chan movies. This came out the same year as Charlie Chan at the Opera, one of the better movies in that series, and might have been one reason he had a role as one of the main characters in this movie, which definitely had better production values than the usual Chan movie.
I would say this movie had a lot of good atmosphere, although it was kind of slow and dull at times. That being said, if you just want a horror movie that is more creepy than scary, this should fit the bill pretty well as an alternative person’s choice to the much more popular werewolf movie series with Lon Chaney that would come out several years after this.