Doctor Glendon (Henry Hull) is a dedicated botanist who doesn't go in for that society life stuff that scientists are frequently thrust into. He leads an expedition into Tibet to find the mysterious mariphasa, a plant that blossoms only by moonlight.
The good doctor does find said plant, and brings it back to London. Yea, maybe he was bitten by a half man, half wolf beast, but who cares? This plant is cool!
Night after night he studies the plant all the while dutifully ignoring his young, hot wife (Valerie Hobson). He meets the strange Doctor Yogami (Warner Oland), who claims to have met him in Tibet. He too was searching for the mariphasa plant but came up empty. It seems the blossom of the mariphasa is the only way to keep the victim of a werewolf bite from transforming. Doctor Glendon doesn't care about that, he's got this awesome plant to look at! And he's got this awesome dentist's lamp to look at it with, too! His young hot wife (remember her?) doesn't mind. Her long lost hunky childhood friend is around to keep her, ahem, entertained.
This was the first werewolf movie. Well, the first talkie werewolf movie. A good movie, but it failed when it came out. People thought it too similar to Dr. Jekyll and Mr. Hyde, which I still haven't seen. Bela Lugosi was considered for Dr. Yogami, who would have been awesome in the role. Though, Warner was pretty good as well. Over the next three years he would play Charlie Chan nine more times then die of pneumonia. I bet he was way better than Sidney Toler. He sucked.
The "werewolf" character took a six year hiatus until reinvented by Creighton Chaney in The Wolf Man. I prefer calling the thing a "wolf man" rather than a werewolf, because historically, a werewolf was a man who made a pact with the devil to gain the ability to transform into a wolf. Not someone cursed to change into a man-wolf hybrid. Whatever. Too many history and folklore classes, I suppose.
Nevertheless, it's a good movie. AMRU 3.5. But it's not the FIRST werewolf movie. According to IMDB, the oldest movie with werewolf as a keyword was Nosferatu, which I've seen, but I don't remember the wolf. I will see a restored copy soon, so I'll keep an eye out.
The oldest surviving "werewolf" movie is called Wolf Blood (1925). You'll hear about it soon.