Possibly the best of the season, and one of my favorite Fifth Doctor stories overall. Its very well written, has a great cast, and features the return of the Black Guardian, who's as sinister as ever.
Nicholas Courtney returns as well after an eight-year absence as retired Brigadier Lethbridge-Stewart, who is now a teacher at a school. This was meant to be Ian Chesterton, but William Russell was unavailable.
This story introduces new companion Turlough, who for this and the subsequent two stories, is being coerced by the Black Guardian to kill the Doctor.
Like I said, it really is a cracking good story with mistaken identities, multiple Brigs, and great performances from David Collings as Mawdryn, Valentine Dyall chewing up the scenery as the Black Guardian, and of course the usual greatness that is Nicholas Courtney.
