Doctor Who: Dark Dimension (2021)

"The Dark Dimension" is a 1993 Doctor Who story by fan scholar Adrian Rigelsford. It was originally titled "Lost in the Dark Dimension" and was commissioned by BBC Enterprises to celebrate the 30th anniversary of Doctor Who in 1993. The story is about the Fourth Doctor's quest to fix timelines that have been altered, and in doing so, he meets the 3rd, 5th, 6th, and 7th Doctors.