Turlough and Tegan Assist The Doctor

While on holiday visiting the Eye of Orion with his two companions, Tegan Jovanka and Vislor Turlough, the Fifth Doctor begins to experience flashes of pain, feeling as though bits of his existence are being removed from time.

In a garden somewhere on Earth, the First Doctor attempts to flee from a peculiar energy form which scoops him up and takes him away. Elsewhere, at a UNIT headquarters building, Brigadier Lethbridge-Stewart (aka The Brigadier) is visiting the Commanding Officer of UNIT, Charles Crichton, when the Second Doctor pays a social call. However, as they reminisce over old times the Second Doctor and The Brigadier encounter the same energy form which whisks them away. The same effect also kidnaps the Third Doctor, driving alone on a British country road in his yellow roadster, Bessie, and Sarah Jane Smith, who has just left her flat to catch a bus – despite K9 warning her of impending danger.

Meanwhile somewhere, in a dark chamber, an unidentified man places figurines of each of those who have been kidnapped onto a playing field. He then attempts to remove the Fourth Doctor and Romana as they are punting on a river, but a temporal eddy prevents this from happening, and the two become stuck in time.

Inside The TARDIS

In the Gallifreyan capitol, the High Council of Time Lords, headed by Lord President Borusa and consisting of Chancellor Flavia and the Castellan, learn of the reactivation of the Death Zone, the abduction of The Doctor’s former selves from the time line, and the drain of power from the Eye of Harmony. They reluctantly agree to call The Master to assist them.

The Master, who is intrigued by their invitation, is startled to find that The Doctor’s past selves are being taken out of time... and only he is ruthless and cunning enough to enter the Death Zone - Gallifrey’s darkest secret - to rescue them. In return, the High Council promises The Master a new cycle of regenerations should he cooperate. Curious by this proposal, he accepts, and so is transmatted into the Death Zone.

The First Doctor and Susan

After reaching the safety of the TARDIS the Fifth Doctor sets the coordinates before he collapses to the floor, leaving a horrified Tegan and Turlough to worry about what is happening to The Doctor. Meanwhile, wandering alone in a twisting maze, the First Doctor encounters his granddaughter, Susan... and a Dalek! They narrowly escape, after being pursued by the Dalek, and discover that they are on Gallifrey. The Fifth Doctor’s TARDIS then arrives in the Death Zone which is discovered by the First Doctor and Susan. Inside the First Doctor and Susan meet the Fifth Doctor, Tegan and Turlough. Together they attempt to determine why they have been brought here.

The Third Doctor finds Sarah Jane Smith just as they are attacked by strange bolts of lightening, and soon encounter The Master, whom they do not believe is working for the Time Lords and so is attempting to help them. This is despite The Master producing a copy of the Seal of the High Council, that was given to him to prove to The Doctors that he is working for them. The Third Doctor believing it to be either stolen or a fake.

The Master then encounters the Fifth Doctor who, accompanied by Tegan and Susan is exploring the Death Zone. But when they are attacked by Cybermen, The Master is temporarily knocked out, by a shot from a Cyberman, and loses the transmat device that he was also given to escape the Death Zone. Foiled by both his attempt at honesty, The Master instead decides to ally himself with the Cybermen.

The Second Doctor and The Brigadier

The Fifth Doctor, on discovering the transmat device before the Cybermen capture him, uses it to return to the Capital, where he is informed of the situation by the Council. The Doctor, suspecting foul play, discovers that the transmat device included a homing beacon that would lure the Cybermen to it, and the Castellan is arrested on charges of being a traitor. Evidence, in the form of the Black Scrolls of Rassilon, purportedly containing forbidden Time Lord knowledge, is then discovered in the Castellan’s chambers. Borusa burns the scrolls and orders the Castellan to be mind probed for interrogation, but the Castellan escapes and is shot down by a Citadel guard. Borusa considers the matter closed, but The Doctor confides in Flavia his doubts. When the two try to find Borusa in the Council room, they find him missing.

Back in the Death Zone the Second Doctor and The Brigadier attempt to enter the Dark Tower, that is at the centre of the Death Zone, through an underground passage. The second Doctor explains to The Brigadier that long ago, the Time Lords transported off-worlders to the Death Zone using a Time Scoop, where they made their captors engage in blood sports. Upon their enlightenment, the Time Lords stopped this horrific practice and forbade use of the Time Scoop. Now, the only point of interest in the Death Zone should be the Tomb of Rassilon, the first and greatest of the Time Lords who gave them the secret of time travel... but someone is using the Time Scoop again, exemplified when the Second Doctor and The Brigadier are attacked by a Yeti.

The Third Doctor and Sarah also attempt to enter the Dark Tower, though they must pass a deadly Raston Warrior Robot, which they are able to do when the Cybermen become a new targets for the Raston Warrior Robot, before using its gear to enter the tower from the top, using cabling to transport themselves across a chasm.

Susan Meets the Fifth Doctor

With the Fifth Doctor having disappeared and Susan straining her ankle the First Doctor and Tegan attempt to enter the Dark Tower through the front entrance, followed closely by The Master and the Cybermen. Inside they have to attempt to solve several logic puzzles including an electrified floor which destroys the Cybermen when The Master tricks them.

Meanwhile, another contingent of Cybermen is attempting to destroy the TARDIS. Turlough and Susan, who are stuck inside the TARDIS due to it being drained of energy, watch helpless as the Cybermen set up a fusion bomb outside.

After encountering phantoms of former companions, that try to warn them off, the First, Second and Third Doctors, The Brigadier, Sarah and Tegan are all reunited in the Tomb of Rassilon inside the Dark Tower, where The Master pulls a weapon on them. The Brigadier however, knocks out The Master before he is able to cause any harm. They then set to work on deciphering an obelisk upon which is written some strange symbols in Old Gallifreyan.

The Master

In the Capitol, the Fifth Doctor, having been refused to return to the Death Zone, is hunting around the President’s office when he stumbles upon a secret chamber, unlocked by a musical tune noted in a painting of Rassilon. Inside the chamber, The Doctor is horrified to discover his old friend Borusa is behind everything. Borusa, fearing the end of his regenerative cycle, has stumbled upon the secret of Rassilon’s immortality, and has used the Time Scoop to bring The Doctor’s former selves together, to enter the Dark Tower and solve Rassilon’s final mystery. Using the Crown and Sash of Rassilon, Borusa commands the Fifth Doctor to do his bidding. After the past Doctors lower the forcefield surrounding the Dark Tower, both the TARDIS, carrying Turlough and Susan, as well as Borusa and the Fifth Doctor all arrive, where Borusa reveals his plans to everyone.

Suddenly, a voice from the darkness beckons. Rassilon, the greatest Time Lord of all, is alive in his own tomb, an ethereal presence in the shadows. President Borusa demands immortality. Rassilon asks The Doctors if Borusa is worthy of this gift, and all say no - all except for the First Doctor, who inexplicably agrees that Borusa is indeed worthy. Borusa receives his gift - immortality is granted as he is encased in stone in the sides of Rassilon’s tomb, there to spend forever in isolation and despair.

Rassilon then asks The Doctors if they wish immortality too, and naturally, they turn down the offer. The Master vanishes, as Rassilon notes that his crimes will find their punishment elsewhere; Rassilon also frees the Fourth Doctor and Romana from their time loop, before vanishing into the ether. The First Doctor is very pleased with himself; he suddenly realised the true meaning of the Old Gallifreyan phrase on the obelisk, ‘To lose is to win, and he who wins shall lose’. He takes Susan into the TARDIS, as does the Second Doctor with The Brigadier and the Third Doctor with Sarah - before it splits into four forms, the first three vanishing into their own times and journeys.

Chancellor Flavia then arrives with a contingent of Gallifreyan guards to find just the Fifth Doctor, Tegan and Turlough. Flavia notes that The Doctor has evaded his responsibilities for far too long, and with Borusa now being noted as ‘unavailable’, The Doctor must take his place as Lord President of Gallifrey (which had been bestowed onto him in "The Deadly Assassin"). The Fifth Doctor, unhappy with the task, tells Flavia to return to the Capitol and that she has full deputy powers until his return. The Doctor then takes Tegan and Turlough and flees to the TARDIS. Inside Tegan cannot believe that The Doctor prefers to go on the run in a rackety old TARDIS. The Doctor, however, smiles and observes that after all, that’s how it all started.