The Pit

The Pit was the fifth episode of Season 29 of Doctor Who

Plot
Bored and looking for adventure of her own choosing, Bernice asks the Doctor to take her to the Seven Planets of the Althosian System. A former system of colony worlds that gained its independence, the system vanished before Benny's birth, and no one knows why. Catching the Doctor's attention, there is no mention of the system in the TARDIS memory banks or his own prodigious memory. En route, the TARDIS experiences some interference, then stalls out, before making a rough landing on a large, unnamed planet in the system. Determined to find out what is affecting the TARDIS, the Doctor explores the jungle.

Elsewhere, a scientist named Jarak is studying the water and life on the planet, which is ordinarily off limits. He witnesses the river turn red, then dies from exposure to it; the redness spreads onto the land, and anything it touches seems to be frozen in time. His wife Ell is forced to hide in their interplanetary ship. Yet elsewhere, two shapeshifters, Butler and Swarf, have stolen "Pandora's Box", the most powerful nuclear weapon in history; if used, it will destroy the entire system. Using a team of telepathic Khthons, the system's natives, they are transporting the device through the jungle to an ancient and forbidding castle. In pursuit are a team of hunter-killer androids — Thomas, Chaney, Marilyn, and their leader, Spike — sent by the Archon of the Althosian system and his Justice Police from the capitol world, Nicaea, to recover the bomb. As they skydive onto the planet, their ship — with hidden orders of its own — begins a long but fatal countdown.

On Nicaea, and other worlds in the system, the situation is degenerating. An unwarranted military buildup has left the people starving, which in turn has caused riots that are just beginning to get out of hand. While the Archon and his Justice Police administrator, General Kopyion, deal with the crisis, Major John Carlson has a problem of his own to investigate: a strange series of murders. The investigation leads him to one Bulbir Singh Mann, a dealer in Earth relics and antiques, who took a book of poetry from the scene of one of the murders. He arrests Mann, but is forced to release him upon the interference of a politician, an Academician named Brown, who leads the opposition faction in the governing Academy. Kopyion tells Brown that the most recent victim was an undercover Justice Police officer on an unrelated investigation, confusing the Major.

Spike strikes the planet apart from his fellows, and is mortally injured; he will die in sixty hours. The Doctor and Benny happen upon him, and he takes them for the shapeshifters and holds them at gunpoint. However, the Doctor suddenly vanishes, leaving Benny in Spike’s possession. They are intercepted by the other androids, who cannot risk that they may be the shapeshifters, and open fire. However, Spike escapes with Benny, still believing that she is a shapeshifter. He takes her with him by raft down the river, in search of the bomb.

The Doctor falls through a hole in time, finding himself in a hellish underworld of sorts. He is captured by a race of creatures called the Cun, who force him to fight another creature while they bet on the outcome. He survives, but with injuries, and in the cells he meets the poet William Blake, who also fell through a hole in time. Blake believes they are in Hell, and who can argue? They escape and head for the hole in time, but are intercepted by creatures on pterodactyls. The Doctor bargains for freedom, but is disturbed regardless; the creatures spoke ancient Gallifreyan.

On Nicaea, Brown confronts the Archon in the Academy and attempts to restore order, but fails. The Archon retreats to his palace, but is killed during the night, in the same ritualistic fashion as the previous murders. The chaos accelerates, drawing in military and religious elements; the priests are insisting it is the end of time, the final battle against the demonlike Hunters that are native to the system. While Carlson tries to deal with the situation, his wife Melanie leaves him, volunteering as a nurse in the combat zones.

The hole in time takes the Doctor and Blake to London during Jack the Ripper's murder spree, seventy years after Blake’s time. Blake is disillusioned that the progress he and his compatriots predicted has not swept the world. Their search for answers leads them first to a brothel, where the Doctor's plans do not work out, leaving him disillusioned; his sonic screwdriver is then stolen, and in recovering it, they are captured by a cult whose members worship evil forces. They escape just in time to avoid being sacrificed, burning down the cult's lair in the process. They find another hole in time, this time landing on present-day Salisbury Plain, where they are immediately picked up by UNIT. Verifying the Doctor's credentials, the UNIT officers let him in on current events; they are assisting an archaeological dig which has unearthed the bones of a massive, reptilian creature, much larger than any dinosaur. The Doctor suspects it is only dormant, not dead, and insists that it be destroyed, but the archaeologist, Roberts, refuses. The Doctor realises Roberts is a member of the cult he just destroyed in the past, and Roberts tries to kill him. A group of Hunters — the same as the ones in the Althosian system — interrupt, appearing through the hole in time and crashing a plane, which diverts UNIT to trying to save the passengers and kill the beasts. The Doctor, with Blake, steals the carrier holding the bones and drives it back to and through the hole in time. They find themselves back in the netherworld.

Butler stalks the androids through the jungle, killing first Chaney, then Marilyn. However, before he can kill Thomas, he falls into the encroaching red weed that has spread from the river, and is frozen in time. Thomas finds the ship in which Ell hides; she joins him outside, but destroys the ship, claiming there was a bomb aboard. Thomas knows this is suspicious, but has no time for that, and takes her with him.

Benny falls into quicksand, but is rescued by an invisible figure. She and Spike then find a crashed, ancient space station near the castle, and explore it. Swarf discovers that Butler is dead, and goes to the space station to take revenge. He nearly kills Spike, but Benny escapes; Swarf returns to the castle. Meanwhile, Thomas and Ell discover that many things on this planet, including much of the plant and animal life, are artificial; they were manufactured by Mirage Enterprises, a company owned by Kopyion. They find Benny in the space station, and she tells them that Spike is dead, although she is not aware that the android survived.

Mann, the antique dealer, meets Brown at Brown's apartment. Brown was the expected buyer for the book of poetry; together, they remove its binding to find packets of a potent drug, Dream B, which they sample. As their drug-induced visions wear off, an intruder shoots them both, killing them. Later, Carlson wants to investigate the murders, but Kopyion stops him and closes the case, tying it to the dead officer's investigation. Carlson is not happy, but is interrupted by a notification that his wife was killed in a government-approved chemical attack on the rioters. In a rage, he tears apart the file room, but finds nothing useful there. He follows Kopyion to the spaceport, where Kopyion declares these "the final days", and takes a ship to the unnamed planet. Carlson accuses Kopyion of the murders — correctly, as it turns out — but before he can stop Kopyion, Kopyion kills him.

The Khthons sense the approach of Benny, Ell, and Thomas to the castle. Ell has them surrender so as to get inside quickly; the red weed is closing in. En route to the castle’s cells, Benny notices that the walls are decorated with the Gallifreyan Seal of Rassilon. At Swarf's direction, the Khthons have used the bomb to power a dimensional drilling apparatus, which they now activate, trying to open a dimensional gateway to the netherworld. Swarf's interest is financial; the netherworld is the source of Dream B, which he will sell. Outside, the Hunters gather, and one carries the dying Spike to the castle; he kills the Hunter holding him, and makes his way slowly inside.

The Doctor reveals to Blake that the netherworld is the home dimension of the Yssgaroth, the Great Vampires of archaic Gallifreyan history, which the Gallifreyans once allowed into the universe, thus kicking off their great war. Now the Cun and others are establishing a bridgehead for the Yssgaroth to invade again, and in the process they are mining Dream B, which the cult on the other side uses in its rituals. He tries to use the Dream B, which is explosive, to destroy the bridgehead, but before he can do so, he and Blake are spirited away. Their rescuer is Kopyion, who is more than he seems; he is Kopyion Liall a Mahajetsu, the nearly-mythical Gallifreyan general who led the war against the Yssgaroth, millions of years ago. He claims that Rassilon's early experiments with time travel opened the gates that allowed the Yssgaroth into the universe; after the war, Rassilon hid the truth, against Kopyion's will. Therefore, Kopyion has waited all this time for the monsters to return — and now it is happening. He is willing to carry out his plan against them even if it costs Benny's life.

Escaping the cells, Thomas, Benny, and Ell head to the courtyard where the drill is running. There, Ell reveals that she and her husband were Nicaean members of the Yssgaroth cult, as were the now-deceased Brown and Mann. It was they who hired Butler and Swarf, in order to gain access to the netherworld. Thomas tries, but fails, to kill Swarf, who instead kills him. Ell then kills Chopra, the final surviving khthon, in preparation for the arrival of the Yssgaroth. Kopyion prepares to deal with Ell, but Spike arrives, and destroys the drilling machinery.

Some small part of the bomb's force radiates outward, bringing down the castle; it crushes Ell, and Kopyion then beheads her for good measure. Most of the explosion has flowed through the gateway, causing incredible destruction in the netherworld and closing the gate for now. The Doctor argues with Kopyion over his methods; Kopyion insists his resolve is strong, and he will stand against the Yssgaroth regardless of cost. To prove his point — and to close this gateway for good — he reveals that he is allowing the androids' ship to self-destruct; its explosion will destroy the entire system, including this world and its gateway. Benny objects, but the Doctor reminds her that they are already aware of the destruction of the system, and thus part of events—therefore they cannot avert the destruction. Kopyion erases this information from the Time Lord Matrix, deeming it too dangerous. He warns the Doctor to stay out of his way in the future, as he will kill the Doctor if he sees him again. Before the system goes up in flames, the Doctor and Benny take Blake back to the TARDIS, then take him home.

Characters

 * Seventh Doctor
 * Bernice Summerfield
 * General Kopyion Liall a Mahajetsu
 * William Blake
 * Butler
 * Swarf
 * Chopra
 * Archon
 * Spike
 * Thomas
 * Marilyn
 * Chaney
 * Major John Carlson
 * Bulbir Singh Mann
 * Academician Brown
 * Jarak Romer
 * Ell Romer
 * Melanie Carlson
 * The Fellowship
 * Colonel Philips
 * Yssgaroth

Astronomical objects

 * The Seven Planets are in the Althosian system.

The Doctor

 * The most pious person the Doctor has ever met is a French Jesuit missionary in Africa.

Gallifrey

 * The Seal of Rassilon is an ancient symbol for warding off evil.
 * Gallifrey literally translates to "they that walk in shadows".

Writers

 * Susan loved the works of William Blake.
 * William Blake fell through a portal in 1811.

Animals

 * The Doctor once had a marmoset thrown at him by a Cun.

Continuity

 * State of Decay introduced the legend of the Time Lords' war against the Great Vampires. General Kopyion is revealed as Kopyion Liall a Mahajetsu, the legendary Time Lord who led the war.
 * Rassilon's experiments and the war with the Vampires are further outlined in Interference - Part Two.