The backstory from the helpfile.
Shadowgate--ancient keep of the Circle of Twelve--stands guard, a lone sentinel: waiting and watching for your arrival. You are the "Seed of Prophecy," destined to fulfill the oracles of the ancients.
Reclaim the castle and free the world from the throes of the Warlock Lord. If found worthy, your name will be honored throughout time. If not, you will never be heard of again.