Tags: Doctor Who
A very long story, spanning 12 episodes, it is an extensive delving into the ultimate goal held by the Daleks. Namely the EXTERMINATION of everything which is non-Dalek. A prequel was shown, "Mission to the Unknown", which didn't even show The Doctor at all. Instead it showed a group of military men on a mission to a jungle-filled place where some of the plants had a special poison which converted people into more instances of those plants. A very rugged and dangerous place full of death and Daleks, but no time travelers. In the Master Plan we see there is an empire of several intergalactic races of beings. It's a little confusing because Mavic Chen is said to be the Guardian of the Solar System but at the same time that role places him in leadership over the whole conglomeration of intergalactic cultures. Either they mean something else by 'Solar System' or, well, I'm just confused.
In any case what we learn quickly is that there is a revolution brewing. Some of the races making up this conglomeration of civilizations have allied themselves with the Daleks. These supposed partnerships are meant to change the power structure, and in secret Mavic Chen is joining these rebels and his payment is material which will form an integral part of the Time Destructor. It seems the Daleks believe if they destroy time it will destroy everything other than themselves and they'll be ruling the universe.
The Doctor and companions land on the planet where these conspirators are meeting. After some circumlocutions the Doctor sneaks into the gathering and learns about the plan. He manages to steal the crucial material and make off with Mavic Chen's "spar" (whatever a "spar" is.. it's purpose is to fly through space, so it's really a space ship). They're able to make their way back to Earth to attempt to warn officials back home that Mavic Chen is betraying his own people. But they only learn that Mavic Chen has coconspirators.
Along the way we have the first death of a Companion. The lady they'd picked up in ancient Troy was captured by some of their enemies and being used as a hostage. Rather than allow the hostage situation to make the Doctor do something he'd better not do, Katarina pulls a lever that opens an air lock and sends herself and captors into space.
The story makes broad jumps back and forth between planets and even time. At one point the Doctor and companions (who later includes Sara Kingdom, one of Mavic Chen's coconspirators) are in the TARDIS being chased by the Daleks. This chase is through time and space just like the earlier series, The Chase. One place they spend some time is in Ancient Egypt dodging around the pyramids with the Daleks in pursuit.
Another event is the Doctor making a faked copy of the Taranium (the special element required for the Time Destructor) which he gives to the Daleks leading them a bit astray when they try and use it in their machine. Eventually however they do get the real Taranium.
During the chase they encounter the Meddling Monk and have various interactions with him including a short period of being allied with him. A curious thing is that the Doctor steals from the Monk the directional controller in his TARDIS. The Monk is later unable to control when or where his TARDIS goes, however when the Doctor hooks the directional controller to his TARDIS it blows up. I suppose the writers really need for the Doctor to be flying at random through time and space.
Eventually we come to the end .. where the Doctor himself activates the Time Destructor and he and Sara Kingdom run away while holding it. Its effect is to rapidly age them eventually causing Sara to disintegrate. Steven rushes outside and tries to deactivate the Destructor, but cannot do anything. As he begins to rapidly age, he tries to help the Doctor, but is ordered to get back into the TARDIS. Fortunately, when trying to deactivate the destructor he managed to reverse it, thus causing the two to revert to approximately their previous ages. The pursuing Daleks try to destroy the Destructor with their weapons but instead cause it to run uncontrollably fast, destroying the Daleks and reducing the planet to a lifeless, barely habitable wasteland. The Doctor and Steven emerge from the TARDIS some time later, the Destructor having burnt itself out. "What a terrible waste..." mutters the Doctor, referring to the death and destruction that has taken place.
I think the thrust of the story is about the extent to which grasping at domination can be taken. Their desire to dominate is so strong they're willing to destroy the universe. Amazing.