Based on The Feral Dog from the Age of Worms. In my campaign it is an old trading post by the sea converted to an inn.
The innkeeper is a half human / half hag. His mother is an old seahag living in the inn.
The innkeeper's father was an old seatrader, who actually fell in love with a sea hag (!). They ran away from the coven, but was cursed by the two remaining hags.
He (the seatrader) tried to kill the two hags in order to break the curse, but was killed and turned into a ghost.
The curse can only by broken, and the ghost laid to rest, if the two hags get an offspring from the seatrader and his wife hag. When the pcs arrive, the innkeepers wife is about give birth to grandchild of the seatrader and the hag...
In my campaign the pcs had to travel to Skull Island and break the curse by fighting the hags. My interpretation of Skull Island is also published here at DungenFog. I used "Underwater Den" by Inkubus as the seahag lair.