I'm not going to lie; the first episode of the story collectively known as The Keys of Marinus damn near led me to skip the whole thing. The first scene, with the TARDIS party exploring a glass beach bordering on an acid sea (Susan nearly loses her feet by going paddling in it), augured well, but then as the travelers explore a huge edifice, the exact same revolving wall stunt as famously depicted in Young Frankenstein above is used no fewer than 4 times, and is meant to be thrilling and suspenseful each time it's employed.
Strange men in bat-themed rubber suits stalk the TARDIS party, and--
Oh, it was dreary beyond words.
Then, we are given an exposition dump by a tragically wasted George Coulouris as Arbitan (who is then subsequently tragically wasted, getting knifed by a bat-suit). In the exposition dump, we are told:
DOCTOR: Yes, yes. I want to know more about this planet. Your technology, you say, reached its peak over two thousand years ago?Yeah, good luck. The travelers return to the TARDIS, only to find they can't get in--an invisible field prevents their entry. After an improv exercise straight out of Mummenshanz (Susan's field is further out from the TARDIS than everyone else's; Hartnell prods his with his walking stick, with weary air of resigned disgust that almost saves the scene), Arbitan's voice is heard saying he'll let them in if they bring him the keys, and he's really quite sorry, but--no, he's not either. They accept the watch-like travel devices that let them jump from place to place (but not time to time, so not vortex manipulators), and the assignment.
ARBITAN: Yes, and all our knowledge culminated in the manufacture of this. At the time, it was called the Conscience of Marinus. Marinus, that is the name of our planet. At first, this machine was simply a judge and jury that was never wrong, and unfair. And then we added to it, improved on it, made it more and more sophisticated so that finally it became possible to radiate its power and influence the minds of men throughout the planet. They no longer had to decide what was wrong or right. The machine decided for them.
DOCTOR: I see. And in that case it was possible to eliminate evil from the minds of men for all time.
ARBITAN: That is exactly what happened. Marinus was unique in the universe. Robbery, fear, hate, violence were unknown among us. Yes, yes, for seven centuries we prospered, and then a man named Yartek found a means of overcoming the power of the machine. He and his followers, the Voords, were able to rob, exploit, kill, cheat. Our people could not resist because violence is alien to them.
(A Voord is eavesdropping on all this)
IAN: But surely by this time this machine had become a great danger to you? If it had fallen into the hands of the Voords, they could have controlled Marinus. Why didn't you destroy it?
ARBITAN: We always hoped to find a way of modifying it and making it again irresistible. So instead of destroying it, we removed the five key microcircuits.
IAN: What did you do with them?
ARBITAN: One of them, I kept. There it is. (points up) The other four were taken and put in places of safety all over Marinus. Only I know where they are, and now the time has come when they must be recovered.
BARBARA: Well why don't you simply make new keys?
ARBITAN: The keys are very simple, but the microcircuits inside are very complicated. A permutation of numbers and signals that would take a thousand years to unravel. And besides, since the keys were hidden, I have worked on this machine and modified it, so that when they're replaced
DOCTOR: When they're replaced it would mean that your machine is irresistible and you can overcome and control the Voords again.
IAN: Surely there must be someone you can send for these keys?
ARBITAN: Through the years all my friends, all my followers, have gone. They have never returned. Last year I sent my daughter. She has not come back. All I have now to comfort me is the distant echo of her voice, the imagined sound of her footsteps. But now your coming's brought new hope. Oh yes, yes, you must find the keys for me.
So the reluctant travelers set out--and then Arbitan is killed, as hinted above, by a diver in a bat-themed gimp suit, who stabs with all the earnestness of Bobby Jindal.
We move on.
Things take an immediate turn for the better; Barbara, having preceded her companions, greets them from a Roman-style couch, garbed in Roman-style robes, queening it up, with serving women attending her every whim. Jacqueline Hill plays it to the hilt--Barbara is relaxed for the first time since Coal Hill, and grateful to have, as she thinks, fallen into the hands of a culture that desires only to please its guests. So, at any rate, she has been told by Altos, a young man, and Sabetha, who is the chief of the serving women. Susan wants a dress made from some of the fine bolt of silk Barbara has been given, and the Doctor wants a laboratory. Ian alone is skeptical, wondering when the bill will be presented.
In the morning, Barbara is horrified--all the beautiful objets d'art with which she has been surrounded are revealed as cheap, dirty stuff, her dress a simple shift, and the fine crystal dirty mugs. The other travelers look at her as if she's gone mad. Barbara flees, and evades Altos, who seeks to take her to the physician.
If, by the physician, you mean the lead of four brains, with tapered stalks supporting their eyes, that reside in bell jars and have enslaved the populace through hypnosis. (The effect is rather delicate, and not bad at all.) The brain declares that Ian and the Doctor will work for them, Susan will be trained as well, and Barbara--well. she knows the truth so hypnosis won't work on her anymore. Just kill her. And Sabetha, too, who didn't put Barbara under properly.
The rest of the episode is the Barbara Wright Show, as she circumvents Altos, rouses some vestige of independence in Sabetha, and is strangled by Ian, now fully under control. This last is disturbingly well done; William Russell goes after her pretty hard, and Hill fights back just as hard. She wins, and attacks the bell jar with a tool. This goes a little less well, as some of her blows are obviously ineffective. Still, Barbara operates on an old maxim of Harry Flashman's--keep striking until something breaks. She kills the brains, the peasants revolt (quite loudly), and Altos and Sabetha--agents of Arbitan (indeed, Sabetha is his daughter) join with the TARDIS crew going to the next of the four destinations. Except for the Doctor--he's off to the final destination...
Jacqueline Hill is the star of the episode, and carries it well. She even does the action hero stuff usually left to Ian, who is marginalized and then weaponized against her. Hartnell's Doctor is easily seduced by the lure of the perfect laboratory, and believes a battered old mug will help him fit the TARDIS. Hartnell sells the Doctor's greed for knowledge here, but, near the end of the episode, his cool decision-making. He's crisp throughout this one. Carole Ann Ford is quite good too, and William Russell sells both Ian's threat to Barbara and and his horror when he comes to.
The Screaming Jungle, though, dips back into mediocrity for most of its duration. Terry Nation has good ideas, but pads them out like he's writing for Dark Shadows. Oh, well. Susan arrives first, and is deafened by, you guessed it, the screaming of the plants. By the time the others join her, they've stopped, but Susan is in full scream mode. (A scream-off between Carole Ann Ford, Bonnie Langford, and Walter Koenig (yes, I mean it) would be a damned close-run thing.) Barbara finds the key (yay!) but disappears (boo!), and then Sabetha realizes it's a fake key (oh, crap.). So everyone else goes off to meet Barbara (in case she's used her travel device), except Ian. Who finds her, fights some plants, including one that looks a bit like Audrey. Barbra finds the key, based on an inspiration of Ian's, they teleport away, and--
Are freezing to death on a windswept mountain.
Bloody Terry Nation.
Here we go...