Looking for a film I started but had to pause halfway through and forgot all about it.
It's about a woman who barely goes out and calls her father "the captain" and was lost at sea, and has a penchant for tying up random guys and killing them by chopping their dicks off. I got halfway through and it's heavily implied she had an incestuous relationship with her father but is prim and proper at all times with her two nephews. The film starts with the three of them playing on a beach.
The title has "sea" or "mermaid" in it,
Found it myself after scrolling through 3000 films tagged with "incest"
If I can't close this, mods please lock/move.