I just watched this movie on NetFlix. It was VERY interesting and pretty creepy. It's about a woman whose father had been searching for the literal philospher's stone -- a material that can heal injuries and change lead into gold. She ends up going into the catacombs of Paris, France with a friend and a bunch of strangers to look for the stone. As they go deeper, the group discover that the tunnels are occupied by strange pale skin cultists that at first seem almost oblivious to their presence. Then as they go deeper very paranormal stuff starts to happen.