Colin Baker only had a two broadcast years stint as the sixth Doctor. In the profile of this Doctor on DVD 2 of The Doctors Revisited 2, he is described as the darkest and most unpredictable of the incarnations. That is not something you can see in Story 138 of the series, Vengeance on Varos, a story told in two forty-five minute segments.
The Doctor and Peri (Nicola Bryant) land on Varos, a mining planet which is ruled by a governor whose tenure is constantly re-evaluated by television referendum. The only other thing to watch is the executions of various supposed criminals who have tried to change things. The current governor is trying to negotiate a better price for Varos' ore with with Sil, a sluglike creature who knows the real value of the ore.
The Doctor and Peri upset the apple cart, of course, but not before a few chase scenes and missed executions.
What holds the episode together is the reactions of two Varosians who are watching the events on their television. It is their comments at the end of the story that kind of give it purpose.
Like all other stories in The Doctors Revisited, the Vengeance on Varos DVD features both the original two-part fullscreen version and a full-length widescreen version of the show.
The other stories on Volume 2 are Earthshock with Peter Davison, Remembrance of the Daleks with Sylvester McCoy, and the Paul McGann Doctor Who movie.
Our review of The Doctors Revisited Volume 1