Oblivion: The Shivering Isles förglott

Upon installing The Shivering Isles on your platform of choice, you will simply enter the world of Oblivion as normal. Twenty four hours later, you will get wind of a rumor that a mysterious door has appeared on a small island in the middle of Niben Bay, which is marked on your compass. A bit of walking (or, better, teleporting) later, you'll discover the structure in question, a large grotesque three-headed statue with a glowing blue portal set into the middle head's gaping maw and a few NPCs hanging around outside. One of the NPCs refuses to speak with you, another appears to be insane, and the third informs you that, having entered and reemerged from the portal, the second NPC is insane.