Here's a fun story: After completing all of the location filming for Inferno, director Douglas Camfield had a heart attack on the first day of studio filming. He wouldn't admit it, though. He insisted on continuing to work despite being white as a ghost and clearly on the verge of collapse. Producer Barry Letts was called down to the sound stage, and upon seeing Camfield's state Letts informed him in no uncertain terms that not only was filming over for the day but that they were going directly to the hospital. Camfield likely would have died otherwise, and Letts assumed all directing responsibilities for the remainder of the filming. As an added twist, Camfield's wife Sheila Dunn had been cast in the leading role of Petra, the dickish scientist's assistant. What had supposed to have been a pleasant working collaboration turned into a very draining shoot as she shuttled back and forth between the sound stage and the hospital. Due to contracts, though, Camfield retained sole credit for directing the story.

As for the conclusion to that story? Well, let's talk about that.

Inferno - Episode 7

(TARDIS Data Core recap)

The final episode picks up with the Doctor unconscious on the floor back in the main reality, where Liz finds him and notifies the Brigadier immediately. Although it takes the Doctor some time to awaken from his comatose state, of course once he does he is able to avert the disaster that befell the Mirror-Mirror dimension. Speaking of which, the opening also specifically never shows the final fate of the three doppelgängers left behind. One presumes they were all incinerated under the approaching lava floe right after the Doctor made good his escape. Poor souls.

A lot of the scenes in the last episode nicely parallel scenes that had happened in the alternate dimension, except with the Doctor making the correct choices to avoid the terrible fate. In the end the world is saved, of course, after which the Doctor butts heads with the Brigadier. He calls the UNIT leader a "pompous, self-opinionated idiot" before transporting himself away again with the TARDIS console. Unfortunately for the Doctor, it turns out he is only transported a few seconds ahead in time and a few hundred yards away into a pile of garbage. He is forced to come back and eat his own words, and then make nice with the Brig as the final credits for the season roll.

I will say without reservation that Inferno is easily my favorite Third Doctor story thus far. That being said, I am very much relieved that it is also the very last seven-parter ever done. There are a number of six-parters coming up, but from here on out that is the longest any story ever runs. 

Oh, and here is a fun story for you:  On the first day that Nicholas Courtney filmed as his evil counterpart, his opening shot had him sitting in a chair with his back to the camera. Then he would slowly spin around to reveal himself without the mustache and with the eye patch and wicked scar. The rest of the cast and crew decided to have a bit of fun with him, and so when he spun around on the first take he was confronted with a room full of people all wearing eye patches. To his credit, he never broke character. He simply carried on with the scene and portrayed the requisite loathsome menace while delivering his lines. Years later, when Courtney passed away in 2011, showrunner Steven Moffat paid tribute to him in the episode The Wedding of River Song by writing a scene in which everybody wears eye patches.

Rest well, Brigadier

Next up: Goodbye Liz, hello Jo Grant, and.... (drum roll please)  hello to the Master!

STATS:

Doctor(s): Third
Companion(s): Liz Shaw, Brigadier Lethbridge-Stewart
Episode(s): Inferno - Episode 7
Steps Walked: 6,934 today, 954,439 total
Distance Walked: 3.57 miles today, 465.55 miles total
Weight: 265.36 lbs (five day moving average), net change -41.94 lbs