The Three Doctors aired from December 1972 to January 1973 during the time of Jon Pertwee's run as the Third Doctor.
The story involves a lost member of the Time Lords, Omega, the engineer who figured out how to harness the power of a black hole to give the Time Lords enough power to be able to travel in time and space. Believed lost he existed in an "anti-matter" universe created by his own force of will. He began draining all the power from Gallifrey (the Doctor's home world) and leaving the Time Lords helpless. The only one not affected was The Doctor who was on Earth in exile.
The Time Lords realized that only the Doctor had a chance of stopping Omega, but not a great one, so they figured if one Doctor had a chance, then two Doctors had double the chance, even if it meant breaking the First Law of Time. Something even a renegade like the Doctor was unwilling to do himself.
The story was a great one to be honest and I recently had the chance to rewatch it. William Hartnell even got to reprise his role of the First Doctor, despite being in very ill health. The rapport between Patrick Troughton (the Second Doctor) and Jon Pertwee (the Third Doctor) was just so much fun it made me wish we could have seen more of them together.
It also set the stage for more multi-Doctor shows to occur for the anniversaries of the show, though not always.
Complaining about the special effects from the time feels like a cheap shot, so I will not do it, instead, I want to focus on the story and the acting. Nicholas Courtney was at his very best as Brigadier Lethbridge-Stewart. He played the role with such convincing annoyance at the Doctor (all of them) and confusion he stole every scene he was in. Katy Manning was wonderful as always as Jo, and John Levene gave us his typical strong turn as Sergeant Benton. Though I understand Frazer Hines was due to return as the Second Doctor's companion Jaime and that would have been fun. Thankfully Frazer, and Jaime, get to come back later, and he has some lasting appeal even today.
This is also an interesting one for me. In the 1980s I read all the Doctor Who books I could get my hands on and this was one of the ones I read long before I ever saw it. My mental image of everything was different than what we got on screen, but I was not disappointed.
Sadly this was William Hartnell's last acting role and his health was so poor that his role here was only in cameos. He later died in 1975.
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