I would like a title to an old b&w film. I remember that guests are staying in an old house on a cliftop next to he ocean. During the night a secret door opens in one of the bedchambers and bipedal sea monsters kidnap one or two of the female guests. They go through the secret door down a cavern like passage to the sea. Any ideas I saw this movie when i was a very young boy im 43 now. I really want to see it again.