After walking out of the Main Hall you see Hokas Tokas, the wizard. He says to you, "I have just heard word of a new tyrant named Astrallion. He has the ancient Medallion of the Mind. It was stolen from the Main Hall's treasure room. It has the power of controlling other people's minds. I found the tyrant's hide-out. It is in the Chaosium Caves!
"You must venture into the caves and kill the tyrant. Once you are in the caves, you will not be able to leave until you get the medallion."
He makes a gesture with his hand and you find yourself in the caves!
This adventure is part of the Eamon universe. Like all Eamon adventures, it is an RPG-style game, mostly using a two-word parser. Because Eamon is a modular system, you may bring a character and equipment from other adventures into this one.
Source: IFDB.