One of my all time favourites! This is the first Third Doctor serial that I can recall seeing (pretty sure I saw some as a young kid, but don’t have too much recollection of them), back on PBS in the 1980s. I love the dynamics of this story and it has always remained in my top serials.

Episode 1:

 The title sequence for the serial is superimposed over lava flowing, cascading.

 The Doctor is driving Bessie, singing/humming some opera song or another. He enters a restricted area industrial plant of some sort or another.

 We see a man arrive on a bike and he goes into a facility, reporting to the man in charge, Sir Keith. He’s a repair technician and #2 pipe is acting up again, it seems. They go off to take a look at it and the tech says it doesn’t look too serious. Sir Keith insists that Professor Stahlman doesn’t want any more delays than necessary. When Sir Keith returns to the control room, Stahlman lectures him on involving himself in the maintenance problems of the drills.

 The technician sees some glowing green effluvium leaking from the pipes. When he touches it, it burns him and changes the skin tone on his hand. Minutes later, he staggers out, almost as if in a trance.

 Stahlman orders for #2 pipe to be put back in service, at an accelerated rate to make up for the cessation.

 The technician staggers across the plant; one of his associates sees him as he partially collapses, leaning against railing. He rushes over to help him but the technician, growling like some primal beast, attacks him for his trouble.

 The next morning, The Brig arrives in an office, shortly followed by The Doctor. Benton has been readying the office for the Brig and they discuss the murder and the search for Slocum, the technician who worked on the pipe. They have the wrench he used to kill the other man, and it’s still hot to the touch.

 The project they’re at is the first penetration of the Earth’s crust, which is why The Doctor requested to be brought along with the UNIT team. He tells the Brig he has some side experiments he’s working on, somewhat related, and goes off to attend to them.

 Sir Keith receives Mister Sutton, a top oil rig man brought in at his request. Even though he’s an oil rig man, and this is very different, Sir Keith wanted someone with some practical drilling expertise there. Sutton finds it hard to believe that they’ve penetrated as deep as twenty miles below the surface, and makes a crack about waking the Devil. Sir Keith shares the nickname some of the technicians have come up with for the plant already – “The Inferno”.

 (Now that we have introduced the title, we can get on with the story, what what?)

 Sir Keith takes him around the control rooms, giving him the tour. He explains that they’re drilling for deep pockets of gas, named Stahlman’s Gas after the professor, which will be a near-infinite storehouse of energy. Sir Keith takes Sutton to meet Petra, Stahlman’s personal assistant, who deflects Sutton’s (somewhat ham-fisted) flirtations. Next, Sutton is led to meet with Stahlman, who is very unhappy at another advisor/expert brought in by Sir Keith.

 The Doctor arrives, just in time for Stahlman to direct some snark at him, too, though the time lord plays it off. Sutton meets with The Doctor, who shares with the oil man his reservations about Stahlman. He routes some power for one of his own projects and then departs, not before getting on Stahlman’s nerves one more time.

 The Doctor drives Bessie to a workroom, where we see his “side project” – the TARDIS console! Liz is there working on it and he hands her some feedback from one of the computers he got while he was there. Liz tries to talk him out of a test run, but he’s adamant in going through with it.

 Slocum, now changed, his body more hirsute, his skin colour and texture changed, is seen rushing about the plant, entering a location where he sneaks up on a man on the phone.

 The Doctor and Liz begin their test run.

 Slocum stands, bloodied. The man is on the floor. Slocum staggers into an adjacent room and pulls down a slide lever on a console, increasing the power. This as an effect on The Doctor and he tells her to cut the power, but she can’t. She turns and watches the console and The Doctor disappear. We see him flailing through some void with all kinds of hall of mirror effects.

 Liz struggles with the circuits and finally manages to flip them. The Doctor and console return to the work room. He says he was in some Limbo, but there was a barrier he couldn’t break through. This only reinforces his desire to try again, but suddenly there’s an alarm klaxxon sounding. They rush off to investigate.

 In the control complex, blast shield doors are being lowered on Sir Keith’s order, but Stahlman rescinds the order. Petra isn’t able to raise the reactor and rushes off to the reactor. The Brig shows up to report that one of his soldiers has been killed, not far from the reactor.

 Stahlman reminds me of several characters in previous serials – mainly from the Troughton era; leaders who won’t listen to anyone because of their precious reputation or ego.

 Petra and Sutton return from the reactor to report the coolant controls are jammed with the heat; Stahlman goes to investigate. At the reactor room, The Doctor and the Brig find the dead technician, and then Slocum jumps out and roars… and the credits roll.

 Like I said, this is one of my faves, I’ve seen it at least five times, as recently as last year. Even though it has a bull-headed man in charge plot device, which I am not the biggest fan of, I do enjoy this one a great deal.

Episode 2:

 The Doctor, Brig and several soldiers face off with Slocum, while Sutton gets the coolant flowing. Slocum is shot several times through the heart, and moves about for more than a minute before he drops and the wall is scorched from where he was propped against it.

 Sutton makes a little headway with Petra.

 The Doctor shares his thoughts about a possible connection between Slocum and the eruption of Krakatoa in 1883. Benton arrives to tell the Brig that Private Wyatt (who struggled with Slocum) and the technician have disappeared before the medics could check them out. Benton and the Brig go off to search for them, leaving The Doctor behind. He sees Wyatt and gives chase, but Wyatt tries to attack him, accidentally falling to his death in the process.

 The technician staggers about, his hands growing inordinate amounts of hair and his skin changing colours as well.

 Sir Keith has some of the green effluvium from #2 pipe collected; he says the lab can’t get close enough to test it, it’s so hot.

 The Brig consults with Stahlman and Sir Keith over the deaths; Stahlman wants nothing to do with what he sees as “personnel problems”. While they argue, the jar of effluvium seems as if it going to crack. Unwisely, Stahlman takes it by hand and places it back in the box.

 The computer warns that the drilling should be stopped immediately, but Stahlman refuses to listen. To punish The Doctor for his temerity, he has the nuclear power to The Doctor’s hut cut off.

 Stahlman shows some signs of illness in regards to his hand. He removes a component from the computer and takes it into the Brig’s office, prepared to destroy it. The Doctor stops him, they struggle, and The Doctor paralyzes him with “Venusian Karate”. The Brig shows up, but Stahlman has hidden the micro-circuit and The Doctor isn’t able to show evidence for his claims.

 The Doctor, having turned the nuclear power back on, returns to his workshop and finds an excuse to send Liz back to use the computer for some calculations that he usually does is his own head. With her out of the way, he begins preparing for another trial run.

 The technician spies Liz from a hiding place as she makes her way to the main facility. Once there, she sees the computer is down and learns from the Brig that The Doctor knew it was down; realising she’s been sent on a wild goose chase, she tells the Brig to accompany her and rushes back to The Doctor’s hut.

 Stahlman realises that someone is tapping the nuclear power and switches it off.

 The Brig and Liz enter the hut just in time to see The Doctor, the TARDIS console and Bessie disappear… and the credits roll.

Episode 3:

 The Brigadier and Liz return to the command center, to ask Stahlman to reconnect the power to The Doctor’s hut, but he refuses. Sir Keith says he must go to London to speak to the Minister.

 Stahlman’s hand is beginning to turn green. He dismisses it when Petra asks if he’s all right.

 Liz and the Brig discuss what’s going on. When Liz says he doesn’t seem very worried, the Brig has an awesome response:

 “Professor Stahlman seems determined to blow us all to kingdom come, The Doctor has vanished into thin air and I have a number of unsolved murders on my hands. I assure you, Miss Shaw, I’m worried.” – The Brig

 We get a swirling effect transition, and we see The Doctor laying prone. His eyes flutter and open and he sits up. The TARDIS console is behind him, and Bessie is there, too. The hut is filled with shelving quite unlike what he had in there – all his equipment is gone. There’s a UNITY IS STRENGTH poster on the wall, and when he tries his automatic door opener, it doesn’t work. He forces the door open and steps out, where things seems a bit more desolate and unkept than we’ve seen before.

 He takes Bessie out, stopping to close up the “technical storage” hut (a label on the door that was not there before), when someone start firing at him. He jumps in Bessie and drives off as two soldiers talk – one of them is Benton! The other tells Benton it was a saboteur, and Benton says to get after him.

 The Doctor drives madcap, trying to escape, soldiers shooting at him. He parks and hides in a trash barrel as the guards run by. Slipping away, he climbs up high and watches the guards scurrying about, looking for him as alarms sound.

 Suddenly, he hears savage growling and a technician (think the one that Slocum attacked?) charges him. The Doctor uses a fire extinguisher to incapacitate the man, but the guards below notice and give pursuit. The Doctor ends up on the roof of the tanks, and finds himself attacked by a savage guard – even though the uniform is different, it’s the same UNIT guard that he fought earlier, the one that fell to his death!

 The guards below open fire and shoot the soldier, who falls to his death (again?)

 A woman in jackboots and dark brown hair marches by; it’s Liz, but her hair is dark and cut different and she’s wearing a uniform. She draws a gun on him and he thinks it’s a joke. Blowing a whistle, Benton and another soldier come running and they arrest him.

 The Doctor is brought in to the Brigadier’s office, but strangely the Brig has an eye patch and no moustache! The Doctor is slow to figure things out, as he talks to “Brigade Leader Lethbridge-Stewart”. When he reveals he knows their names, they accuse him of being a spy.

 Finally, he begins to catch on. For such a brilliant mind, slow to figure it out. He introduces himself as “Doctor Smith, Doctor John Smith”. He tries to tell them the truth – that he’s from a “parallel space-time continuum”. He discovers “Section Leader Elizabeth Shaw” is not a scientist.

 He brings up various names, settling on asking to see Sir Keith or Professor Stahlman. The Brigade Leader brings him to meet with Director Stahlman, who is dressed in all white (like all the technicians there) and has no facial hair, unlike the Stahlman of The Doctor’s proper Earth. They tell The Doctor that Sir Keith died in a motorcar accident twenty-four hours, on his way to London.

 The Doctor asks about the computer; in this world, it’s not working, either. The Doctor makes a comment about the micro-circuit, and Stahlman’s eyes narrow at this. He says the stranger must be to blame for the sabotage on the computer and orders him taken away.

 Sutton, dressed a bit more business-like (not wearing the all white uniforms like the others) than our Sutton, complains to Petra about the lack of pressure in the coolant pipes. He uses her first name and she reprimands him.

 When “Dr. Williams” (Petra) approaches Stahlman about all safety factors being exceeded, he says they are almost there, he will not deccelerate now. He steps away and seems to have an attack, focused on his hand, which is turning green and hirsute, much like his counterpart.

 The Doctor is back in the Brigade Leader’s office, under watch by Benton. When he asks Lethbridge-Stewart what will happen to him, he’s told: “You’ll be shot, eventually.” The Brigade Leader explains that this is his trial and he has the full authority.

 It turns out that the country is a Republic, the Royal Family were executed. The facility is a “scientific labour camp”, staffed by prison labourers. The more The Doctor reveals about what’s been going, the more the Brigade Leader believes (understandably so) that he is a spy. The Brigade Leader informs The Doctor that a search in “Central Records” is being performed, and once they know who he is, the real interrogation will begin. The Doctor protests, “But I don’t exist in your world!”

 “Then you won’t feel the bullets when we shoot you.” – The Brigade Leader, rather chillingly.

 Lethbridge-Stewart is summoned away by a phone call. As he steps out, Section Leader Shaw arrives to tell him that there is no information on the stranger whatsoever. The Brigade Leader steps back in, accompanied by Shaw.

 “You are giving us a great deal of trouble.” – The Brigade Leader

I’m delighted to hear that.” – The Doctor

 As their banter continues, The Doctor insists that the computer, had it not been sabotaged, would be informing them all that they were in great danger, not just himself.

 An issue arises with pipe #2 (familiar, that) and Stahlman refuses to do anything about it (familiar, that, too). Moments later, there’s a rumble and an alarm. Shaw and Lethbridge-Stewart leave to investigate.

 The Doctor escapes, after using some more Venusian Karate on Benton.

 Green effluvium is seen leaking from the pipe. Men put on hazard suits. Some of the men try to escape and the guards pull guns on them. Benton finds The Doctor and tells him to come outside with him, where a firing squad awaits. The Doctor tells him he could fix the computer for them, but Benton says come with him or he’ll shoot him right there. The Doctor stares up at the rifle in his face… and the credits roll.

Episode 4:

 Section Leader Shaw tells Benton to let him try, “we have nothing to lose”. The computer is up and running and Stahlman is dismissive of it. Sutton wants to listen to The Doctor. The alarms keep sounding, other sounds fill the station. Stahlman finally agrees to try what The Doctor suggests. Shaw and Benton take The Doctor back to the Brigade Leader’s office, where she tries to get him to tell “the truth” about himself, though he has been and continues to do so.

 Sutton and Stahlman butt heads (familiar, that) and Stahlman repeats threats intimated by Petra the last time she and Sutton talked – if he doesn’t start towing the line, he could disappear.

 Shaw and Lethbridge-Stewart attempt to interrogate The Doctor, repeatedly asking the same questions over and over – who is he, who sent him, who helped him gain access, who his associates are? The drilling accelerates as the interrogation proceeds.

 Stahlman comes in to check on the status of things; The Doctor asks Stahlman to take off his left glove, revealing a bandaged hand with green showing through. It seems this Stahlman, too, burnt his hand on a jar of the green effluvium.

 The Doctor is taken back to a cell and Stahlman tells the Brigade Leader that he wants the interrogation completed soon and the stranger “liquidated” by the end of day.

 Sutton approaches Dr. Williams (Petra) again, saying more checks should have been performed while the drilling was at minimum revs. Petra isn’t as confident in Stahlman any more, and Sutton takes heart in that.

 The Doctor is taken down to the cells. He sees there’s a prisoner in the next cell, but they’re sleeping on the cot, under the covers. Shaw shows up to continue the interrogation. She dismisses Benton and the other guard. She thinks he’s a political demonstrator – he’s too obvious to be a spy. He rants at her that she’s not as intelligent as her counterpart and she departs, leaving him there.

 The Doctor lays down, not noticing that the person in the next cell over has green, hairy skin.

 We get the sidewards translation effect and see the Brigadier and Liz (non-Section Leader) discussing the missing Doctor. Liz is worried that he’s somewhere in time and space, where the Brig is confident that he can take care of himself.

 Sir Keith approaches Stahlman; he has an appointment with the Minister in London, and is trying one last time to appeal to Stahlman for slower drilling, more safeguards and safety regulations. Stahlman doesn’t react politely to Sir Keith’s attempt to talk first. Sir Keith says there’s something ominous going on. They talk of The Doctor and Sir Keith says, “Well, he’s better off, wherever he is.”

 The sidewards translation effect goes on again, and we’re back in the alternate reality, where The Doctor wakes to the man in the next cell grunting monstrously. He yells for the guard, who enters the man’s cell, but is attacked by the savage technician. The tech bends open the bars and enters The Doctor’s cell, but the time lord manages to get past him and lock him in.

 He slips out of the holding area (wonderful security, that) and skulks about, slipping into a lorry to avoid detection by a troop of soldiers marching nearby.

 The drilling is just over thirty minutes from zero point. Sutton says he can’t help but feel something is going to go wrong and tells Petra they should consult the computer.

 The Doctor finds radiation gear in the back of the lorry, and suits up.

 Three minutes to puncture. Stahlman is acting odd again.

 The Doctor, suited up, joins a group of other men in radiation suits. They head off together.

 The Brigade Leader and his troops stand at the ready as the countdown goes on. Technical personnel are called to final stations. The Doctor enters with the rest of the rad suits. He begins poking around one of the consoles instead of standing with the others, and the Brigade Leader notices him.

 The Doctor pleas at them not to break through the crust. There’s a strange shrill sound coming from the drill, and The Doctor says they have to stop, it’s the planet crying out. Sutton jumps the Brigade Leader and The Doctor tries to escape, but guards chase him back. Stahlman has the Brigade Leader’s gun and points it at The Doctor as the countdown reaches three…two…one… and the credits roll.

 OH DEAR GOD, NOW THAT’S A CLIFFHANGER! And one I’m leaving you with until Friday.