In the 1980s, I heard a recording of a story (probably on an LP) that was either a retelling of an actual European folktale or a modern story written to sound like a classic fairy tale.
I don't remember how it began, but the hero somehow ends up shipwrecked, but before he drowns he is rescued by the daughter of the villain, who is some kind of sea troll king. (He has a proper name, perhaps beginning with H, but I don't remember it.) The two fall in love, and they plot how they will be able to escape from her father together. (They cannot just kill the villain, because he his body is invulnerable; his life force is hidden away elsewhere.)
Their plan is that she will help the man escape, with the villain not having known that he had even visited the villain's undersea realm. Then he somehow finds his was in again, as if he was seeking some kind of assistance from the villain. However, he makes a nuisance of himself and the villain's palace and breaks things. So the villain declares that the hero will be put to death unless he can successfully answer four questions.
However, the daughter knows what the four questions will be in advance:
Where is my daughter? Answer: In a palace at the bottom of the sea.
Then which of these is my daughter? The villain teleports in hundreds of identical looking women, but the real daughter makes a hand signal to the hero so he can identify her.
Where is my life force hidden? Answer: In the heart of a fish in the deep ocean.
Which of these fish contains my life? The villain teleports in hundreds of identical fish, but the daughter, who is still present, points out the right one, so the hero can cut its heart out, dispatching the villain.
Does anybody recognize this story?