The ancient fortress of Trifels was once the heart of Germany. Richard the Lionheart was held captive here. Here, according to legend, Emperor Frederick Barbarossa sleeps eternally in a dungeon. And here lies a terrible secret that can change the fate of all of Europe... Agnes von Erfenstein, daughter of the governor of Trifels, is not an ordinary girl. Unlike her noble peers, she loves to ride horseback around the surrounding area, hunt with a falcon and read old books. And then one day her falcon returned with a gold signet ring attached to its paw. From this moment on, Agnes begins to be tormented by strange dreams about the terrible tragedy that once took place in Trifels. But to all her questions about the past, her father and the local priest only remain silent, hiding their eyes. Meanwhile, suspicious strangers appear near the fortress, persistently interested in some secret connected with Trifels...