The Doctor shouts for help and the Brigadier hears him and runs in and saves him, thus mirroring the scene with Yates saving Jo from the troll. Only the Brigadier doesn't shoot the telephone to bits, he just unplugs it.
The Master makes a grumpy face when the telephone cuts off.
UNIT tracks down the Autons' bus and the Brigadier wants to blow it up. The Autons tell Farrel that they know they are being kept under observation.
The Doctor finds out the plastic daffodil has a plastic brain and it is thinking about "a face, or part of one." Perhaps it's still thinking about the silly face the Doctor pulled at the cliffhanger?
Jo then accidentally wakes it up when she uses the radio to try to contact Yates, and it sprays plastic in her face. The Doctor saves her, and realises that the daffodil was trying to kill her by mistaik, it should have been waiting for a radio signal sent by the Master. A Master signal? He sends Jo off to look at Mr Brownrose's list of other mannys who have been killed and find out if any had daffodils or radios.
Then, when the Doctor is on his own, the Master comes in, descending a spiral staircase, symbolic of his twisted mind, not even bothering with a disguise this time (although his music would have given him away anyhow, he's almost as bad as Jemadah from Watt on Earth). As this is their first face-to-face confrontation, their verbal sparring bears quoting:
"You've come here to kill me, of course."
"But not without considerable regret."
"How very comforting."
"You see, Doctor, you're my intellectual equal. Almost. I have so few worthy opponents. When they've gone, I always miss them."
"How did you get in here?"
"Oh don't be trivial, Doctor. I see you've been working on the Nestene autojet. My own small contribution to their invasion plan."
"Vicious, complicated, and inefficient. Typical of your way of thinking."
When Jo enters and distracts the Master for a moment, the Doctor grabs the dematerialisation circuit from the nearby table and holds it hostage so the Master won't pewpewpew them. Jo tells the Master about the plan to "bomb the quarry."
(You see, the Auton bus is in the same quarry as the fight at the start of episode three, they're not even trying to pretend it isn't the same one.)
The Master forces the Doctor to take the three of them to the quarry in Bessie, so that the Brigadier has to call off the plane that is going to drop the bomb because he doesn't want to blow up the Doctor/Jo/Bessie/the Master (delete as applicable). Instead it just flies overhead, a harmless bit of stock footage.
In the bus, Farrel is starting to resist the Master's hypno-eyes so an Auton knocks him out with a karate chop. Presumably not a Venusian karate chop, more like a Automatic karate chop. They tell the Master
"Farrel became undependable."The Autons tie up the Doctor and Jo, and the Master gets the dematerialisation circuit from him. The Doctor manages to signal to the Brigadier from the bus by making the bus's lights go on and off in code.
"Did he? His father would have been proud of him."
The bus drives back to the radio telescope from part one. Thanks to the Doctor's warning, UNIT are already there with lots of soldiers and guns, but instead of shooting at the bus they just get out of its way as it drives past them. Jo manages to free herself and the Doctor from being tied up, and they jump off the bus.
The Master sends the Autons to shoot at the soldiers and show them how it should be done, while he runs for the radio telescope. On his way up he knocks a scientist off of a high set of steps, because we haven't had enough HAVOC stunts in this story yet.
The Doctor and the Brigadier chase him. When they get to the room, the Master says
"Too late, Doctor. The Nestenes are here!"
Outside there is a blur over the radio telescope, which I suppose must be what the Master is referring to.
"Your precious little planet is finished."
"If we're finished, then you're finished too."
"Nonsense! I helped them to come here."
"Do you really think that that thing will distinguish between you and us?"
By the time we cut back to them from a brief scene of UNIT and Autons fighting, the Master has changed his mind and has teamed up with the Doctor. ROSL! It is always, always great whenever this happens.
"Not unless we change the polarity."Together they do a technobably thing that makes the Nestene blur disappear in a surprisingly anticlimactic way. This also causes all the Autons to fall over and go
"Whilst the transfer shift is still open?"
"It will fling them right out into space."
"You're right!"
There is an unintentionally amusing moment when the Doctor and the Brigadier are congratulating themselves on defeating the Nestenes (again), when the Brigadier suddenly notices the Master isn't there and shouts out "He's gone!" lol.
The Master runs back to the bus and goes inside. Then he comes out again with his hands up. The Doctor says
"Don't trust him, Brigadier. It's a trick."
He tries to pull out a gun but Yates is faster and shoots him first. It's a bit like a shootout in a Western, but an incompetently directed one - the Master goes for his gun when the camera isn't on him. The Doctor takes a mask off of the Master to reveal that Yates has actually shot poor Mr Farrel. The real Master escapes in his bus.
Back in the lab, the Doctor reveals that the Master actually has the Doctor's TARDIS's dematerialisation circuit, which means now they are both stuck on Earth.
"Think he'll turn up again, Doctor?"
"Yes, bound to."
"You don't seem very worried about it?"
"I'm not. As a matter of fact, Jo, I'm rather looking forward to it."
This is a strange, out-of-character moment for the story to end on. While we cats hope the Master will return soon - if we are very lucky it may even be later this season - surely the Doctor should not be looking forward to it, since the Master is "bound to" kill at least a few mannys as part of whatever his next plan is. Oh well, maybe it doesn't count so long as they're not main characters?
What's so good about Terror of the Autons?
The Master.
Roger Delgado is effortlessly magnificent from the moment he first appears, perfectly cast as the Doctor's new archenemy. If this story didn't aspire to do anything more than give him a proper introduction, it still succeeds brilliantly because of Delgado's performance, and this despite the 'tell, don't show' aspect of the Time Lord turning up to tell the Doctor and the viewers about him.
Terror of the Autons has been criticised for its similarity to Spearhead From Space the previous season, which was also written by Robert Holmes. I do not think the similarity is a weakness but a strength - it allows a story of the same length the time to introduce the Master (as well as Jo and Mike Yates, who are also new characters) within a familiar structure. So the Nestene invasion plot is of secondary importance to the setting up of the relationship the Master has with the Doctor via the multiple attempts to kill him.
The pulp-y nature of these, going from each one straight on to the next, is something we haven't really seen much of in Doctor Who since Terry Nation wrote The Keys of Marinus or The Chase. The same is true of the "terror of the Autons" of the title, that shows us lots of different ways that plastic can be made scary, from chairs to flowers to trolls to policemannys.
Of course, the latter of those is more scary in real life these days...