Lost in the Dark Dimension (aka. The Dark Dimension) was a doomed thirtieth-anniversary Doctor Who movie from 1993. It remains a legend in Doctor Who history as being the greatest multi Doctor story that never was, though it may very well have been colossally shit.
A creature made of "chronal energy" fucks around with time so that the Fourth Doctor doesn't die and regenerate after falling from the Pharos Project (as seen in Logopolis). This creates an alternate "dark dimension" and the Doctor has to revert the timeline back before he and his other incarnations are erased from time.
Why it died Edit
With the project sunk, the thirtieth anniversary was instead celebrated with the god-awful Dimensions In Time.
The Caves of Androzani director Graeme Harper was going to direct it and wanted to cast Rik Mayall as the villain.