Hrad stínů (1994)

Prince Thomas longed to prove to himself and his royal parents that he was truly an adult. And on the day he came of age, his father gave him a unique opportunity—an opportunity called Blouzov. Blouzov, an old castle that the prince was to rule alone, was no ordinary place. There were many rumors about it, and they were quite wild. But the truth turned out to be even darker than the speculation. In fact, Blouzov was ruled by the chambermaid Johana with the help of dark forces. She and her equally mischievous son, the water sprite Artur, involved the inexperienced Tomáš in their vile intrigues as soon as he appeared at the castle. And even though he soon gained powerful allies and helpers for his "test of adulthood"—his childhood friend Petr and his beautiful sister Jitka—it was not at all easy to stand up to the evil spells and keep his wits about him at the right moment.