Christopher Lee, plays the head of the Red Dragon tong in a somewhat lackadaisical performance. The MacGuffin is a list of the members of the tong, which a group opposed to the tong could use to destroy it if they can only get their hands on the list. The man with the list hides it in a book before he's killed. The book is a gift for a ship's captain (Geoffrey Toone), and his daughter is killed when the tong members are searching for the list. And it's a good thing. The daughter is so irritating that I was glad that she was in the movie for only a few minutes. I couldn't have taken much more of her.
Naturally the captain wants revenge. The police are no help, so he sets out to destroy the tong on his own. You could probably write the rest of it yourself since it plays out just as you'd expect. The surprise villain isn't at all surprising.
My guess is that 90% of the actors aren't Asian. This might occasion a bit of comment today, but I don't remember that it occasioned any on its original release. What got the comment was the torture and violence, which would now be rated PG at worst. It's all quite mild and nothing graphic is shown. It's an okay movie but nothing you need to go out of your way to see.