The Tomb of Valdemar

Millenia ago, the Vanir ripped a hole in reality and created a gateway to the Higher Dimensions. This resulted in the warping of vast areas of space, and anyone who perceived these Higher Dimensions went insane. The Vanier disappeared into the gateway and all that remains of them is shimmering, golden palace floating in the clouds...The Doctor inadvertently materializes on Ashkellia, where Valdemar's tomb lies. The Doctor must escape imprisonment by Neville, a debauched aristocrat, to save both the universe and himself from the Higher Dimensions.