Propast(1982)

It's New Year's Eve afternoon and Honza, Jana and Zdeněk decide to go out into the karst area. Despite the express ban, one of them goes down into an unknown underground tunnel. When he doesn't return for a long time, the others go looking for him. But they soon discover that they are not enough on their own. Only the best rescuer, Karel Nousek, can save him. However, he is dealing with a complicated life situation. He loves his colleague's wife and is about to solve a love triangle. That evening, Olga wants to tell her husband that she is breaking up with him because of Nousek...