The Magic Springs of Gerenia (1983)

Irene, a agent of an insurance company, is in charge of investigating the disappearance of an old librarian, in a provincial town. In the course of the investigation, she knows Ricardo, a professor of history, who knew the victim and is interested in the legendary traditions of the region. So Irene has the knowledge of the ancient medieval castle - whose secret entrance opens mysteriously on Christmas night during the 12 midnight chimes.