A horror story about four friends who find the entranceway to a network of medieval tunnels beneath Prague. After journalist Renata's (Lucie Vondrácková) colleague disappears in the cellar of her building one night and her Argintinian roommate starts having strange dreams, weird things start to happen in the building. When the two girls and their neighbor Honza (Martin Zbrozek) and friend David (Jan Zadrazil) find the entrance to an underground labyrinth in the cellar and decide to enter it in search of the missing girl, we soon realize that they will have to fight for their lives.