The Time Lords are under attack by an unknown force, and the only people that can help save the Time Lords is the First, Second and Third Doctors.
Written by Bob Baker and Dave Martin
Directed by Lennie Mayne
Main Cast-
The Third Doctor - Jon Pertwee
The Second Doctor - Patrick Troughton
The First Doctor - William Hartnell
Jo - Katy Manning
The Brigadier - Nicolas Courtney
Benton - John Levene
Main Guest Cast-
Omega - Stephen Thorne
Dr. Tyler - Rex Robinson
Ollis - Laurie Webb
Mrs. Ollis - Patricia Prior
Synopsis-
The Time Lords are under attack by an unknown force emanating from a black hole. Losing power rapidly, the only hope the Time Lords have for survival rests with The Doctor.
The Doctor, however, is under attack by the very same force, which is made of antimatter. The Time Lords muster enough energy to take the Second Doctor out of his timeline to assist the Third Doctor. The two Doctors begin squabbling amongst each other, and it's only after the arrival of the First Doctor that straightens things out.
The First Doctor can't fully materialize, being caught in a time eddy. Deducing that the force attacking The Doctor is some sort of "bridge", the Third Doctor and Jo cross over, and are eventually followed by The Second Doctor, Benton and the Brigadier.
The Doctors and their companions find themselves on a world that exists inside the black hole that's ruled by Omega, the Time Lord that caused the supernova that gave the Time Lords the power and ability to travel in time and space.
Omega desires revenge against the Time Lords, but its revealed that Omega no longer has a corporeal body thanks to the years spent in the black hole in the antimatter world. The Doctors eventually agree to stay on the antimatter world with Omega and allowing their companions to return home. The Doctors, however, end up tricking Omega by exposing him to the Second Doctor's recorder, which was not converted to antimatter in the transference to Omega's world. The resultant explosion destroys Omega and his world.
The Tardis returns to Earth, where the First and Second Doctors say goodbye and return to their own timelines. The Time Lords lift their sentence of exile, and the Third Doctor is now able to travel freely in time and space.
Review-
Series/season ten opens with the very first multi-Doctor story, and in my humble opinion still the best multi-Doctor story.
Rather than trying to fit in as many companions as possible (like they tried to do with the later Five Doctors story), in the Three Doctors its just the regular cast (minus Yates for some unknown reason) and the First and Second Doctors.
The "time eddy" story device works well, and allows fans of the series to have one last glimpse of William Hartnell in the role he made famous. The interaction between Patrick Troughton and Jon Pertwee is quite entertaining as well, along with Nicholas Courtney's doubletakes when he first encounters the Second Doctor.
To put it simply, The Three Doctors is one of the most entertaining Doctor Who stories out there and its well worth revisiting over and over again.