Ursula Heyer

The fugitive of a forensic mental institution enters a country house right after the owner changed his last will and a series of mysterious murders starts. (imdb)

When her widowed father remarries, Maria is mistreated by her wicked new stepmother and meddlesome stepsister. One day while walking in the forest, Maria meets a handsome Prince disguised as a hunter. He leaves her with a garnet necklace as a memento of their chance encounter and a symbol of his undying love. But alas, the necklace has fallen down a well and the two sisters plunge headlong into a magical world beneath the water to retrieve it. (imdb)