Son of Frankenstein (1938) is the third in Universal’s 8-movie Frankenstein series. When I was a kid, I always thought the title referred to the son of the monster, but now realize that it refers to the son of Doctor Frankenstein himself. This movie brings together three legendary actors in pivotal roles: Basil Rathbone in the title role of Baron Wolf von Frankenstein, Boris Karloff returning for a third time as the monster, and Bela Lugosi (best known for portraying Dracula) as Ygor. In this movie, the monster wears a kind of wooly, sleeveless vest that looks very strange. This was the longest of the 8 movies in the set at 1 hour 39 minutes.
This film also includes the character of Inspector Krogh, who has a prosthetic arm that he sometimes has to move with his other hand. Young Frankenstein has a similar character played by Kenneth Mars, who plays this up as a nice bit of physical comedy.
I would give Son of Frankenstein four stars. Even with a stellar cast, it’s obvious that the plot lines of the series are starting to degrade. I recommend it, but it’s likely you have other things to watch that are better.