Centuries in the future, the star yacht Crusader touches down on the ruins of the planet Velyshaa. Siy Tarkov, an envoy from the Galactic Union, has arrived with a military escort in search of Saloran Hardew. They find her sleeping in a large chamber full of statues. She is grumpy at being woken, but can’t help but laugh when Tarkov claims that he’s here because the Union needs her help...

It took Tarkov one year to get to Velyshaa; Hardew’s journey took five years, but technology has improved since she’s been gone. She remains suspicious of Tarkov’s motives, and bitter about being ostracised because of her beliefs. She believes that the Great Catastrophe which devastated the galaxy 2500 years ago was the result of a war, and that civilisation was once far superior to what it is now. The Union dismissed her as being obsessed with the past, but Tarkov reveals that two years ago, the Union’s tracking stations picked up a transmission from outside the galaxy, transmitted via a freak wormhole. The message is encrypted, but they’ve broken some of the code and detected what appears to be the image of a machine. Close analysis indicates that the metal alloy matches certain artefact fragments which Hardew found before she was forced to leave the Union behind and carry on her work on Velyshaa. Tarkov admits that he was sent to her because he made a nuisance of himself as well. He still remains loyal to the Union, which has made great strides in improving the quality of life in the galaxy -- but if he wants to make them listen to his warnings he’ll have to take back some pretty conclusive proof.

Hardew agrees to tell Tarkov everything she knows, but he’s surprised when she begins by taking him to the chamber where he found her sleeping -- the burial chamber of a man named Kalendorf. Planets throughout the galaxy still pass down legends and folk tales of a figure called the Dark One, or the Bringer of Death, the man supposedly responsible for the Great Catastrophe; by comparing the legends, Hardew believes she’s identified that man as a Knight of Velyshaa named Kalendorf. According to legend, the Velyshaans were telepathic, and could share their thoughts with other races. This chamber is charged with Kalendorf’s memories, and by sleeping here, Hardew dreams of Kalendorf’s past. She isn’t surprised by Tarkov’s reaction, but suggests that he take a look about for himself before dismissing her as mad. Tarkov humours her, and finds himself drawn to a particular statue which appears to be a machine of some kind. Compelled to touch it, he reaches out -- and is battered senseless by a powerful psychic impression of overwhelming evil. “Exterminate!”

Tarkov regains consciousness in Hardew’s spaceship, a wreck which will never get off the ground again. Following his experience he’s far more willing to listen to her, and she explains that she’s been recording her thought impressions from the burial chamber and that her team has been working to decipher them. Kalendorf left the burial chamber as a legacy and a warning, and when Hardew shows Tarkov pictures of her dreams -- images of a galaxy alive and teeming with people, aliens and technology like Tarkov has never imagined -- he becomes perfectly willing to listen to the whole story.

Hardew thus settles down and tells Tarkov about Kalendorf and his role in the Dalek invasion of the galaxy, from his meeting with Susan Mendes through the years of slavery, the rebellion, the activation of Project Infinity and the alliance and war with the Daleks from another timeline. The story builds up to Kalendorf’s betrayal of the Mentor and his confrontation with Alby on the bridge of the Defiant. Convinced that Kalendorf has brainwashed Suz to support his treachery, Alby tries to shoot Kalendorf before he can make the transmission which will turn the Alliance fleet against the Mentor’s Daleks -- but Suz knows that the transmission must be made whatever the cost, and she shoots and kills Alby before he can kill Kalendorf. As Alby dies before her eyes, the broadcast begins, and Suz has no choice but to pull herself together and address the galaxy, telling them that the Angel of Mercy has returned.

This is the beginning of a terrible and devastating war. The Mentor accelerates her plans for “brain conversion,” while Kalendorf leads the battle against her. As a Knight of Velyshaa he believes in strength of purpose above all other concerns -- and he has a plan to deal with the Dalek Supreme once the Mentor is defeated. However, he probably wasn’t expecting the Dalek Supreme to demand that Suz be handed over as a hostage. The extraction of the Emperor’s mind from her body could take place anywhere, but the Dalek Supreme nevertheless demands that she be sent to Earth and promises Kalendorf that he will see her again when the war is over. Before she leaves, Suz makes Kalendorf promise to win the war whatever the cost, to ensure that she didn’t kill Alby for nothing.

The war drags on for years; the devastation is incalculable, and Kalendorf often takes terrible risks leading his men into battle, as if he wants to plunge himself into the worst the war has to offer. On the planet Meecros V, he finds himself alone on a battlefield, his only company a dying Alliance Dalek which demands to know why he turned his friend over to the Dalek Supreme. Realising that the Mentor is listening through its implants, he tears the living Dalek free of its casing and speaks to it directly, warrior to warrior. There was once a great Knight of Velyshaa named Sancroff, who never feared his enemies but always dreaded betrayal by those he trusted. At the ceremony of Victory or Death, when a knight was promoted into high office, he would look into their minds to see if their thoughts were pure. Only one knight ever betrayed him, one he loved as his own daughter -- and when he learned she was plotting against him, he invited her to his palace to speak to her alone. Nobody ever learned what he said to her, but when their meeting was over, she returned to her fortress, slaughtered her co-conspirators and then killed herself. As Kalendorf tells this story, his new aide, Godwin, finds him on the battlefield, still talking to the Dalek, which died long before he finished.

Godwin and Kalendorf return to the fleet’s flagship, but as they prepare for an assault on an enemy transport fleet they detect a call signal which Kalendorf seems to have been seeking for some time. The signal is coming from an escape pod from the long-lost Defiant, and despite Godwin’s concerns, Kalendorf insists upon crossing over to the pod to investigate. As his capsule approaches the pod, however, both ships phase out of existence momentarily, and although Godwin insists that Kalendorf abandon his investigation and return, communications are lost completely and Kalendorf discovers that the flagship has disappeared. He docks with the pod, but when the airlock opens he finds that it’s one of the Mentor’s craft in disguise -- and one of the Mentor’s Daleks confronts him, revealing that they have extended the dimensional gateway from Lopra Minor and transported him into the Mentor’s universe.

The Mentor seems pleasant enough when Kalendorf is brought before her, but he ignores the small talk and demands to know Mirana’s fate. The Mentor admits that Mirana and Marber died years ago, long before her Daleks found the missing pod -- but she knew that Kalendorf would never be satisfied until he saw the pod for himself. Kalendorf accepts the news of his friend’s death and demands to know why the Mentor has gone to all this trouble to capture him, and is almost amused when he realises that the Mentor just wants to understand when and why he turned against her. He admits that early on in the war his men captured a squad of enemy Daleks and managed to disable one captive’s self-destruct unit. The Dalek released a data virus into its computer core, and Herrick was forced to cut all surveillance links with the cell -- leaving Kalendorf alone with the Dalek just long enough to communicate with it telepathically. He intended to offer Susan Mendes to the Dalek Supreme, and gambled successfully that his captive would transmit the offer via its command net.

This explains when, but not why. The Mentor genuinely doesn’t understand why Kalendorf would reject her offer of peace, even after Kalendorf reminds her of the worlds she destroyed for refusing to join her crusade -- worlds which were simply tired or even incapable of the endless fighting. The Mentor points out that her people are peaceful and content, but for Kalendorf, the price of surrendering his freedom is too high. The Mentor regards this as sophistry, but she admits that their forces have reached a destructive stalemate. If the war continues, the ultimate result will be the destruction of all life in Kalendorf’s galaxy and her own. She gives Kalendorf one last chance to accept her offer of peace, reminding him that his people were unable to defeat the Emperor’s forces alone during the last war. He turns her down, and she gives the order for her Daleks to withdraw from this universe. The war is over.

For a brief time afterwards, it seems that the galaxy is finally at peace. However, few people really expect that the Dalek Supreme will keep its word, and when Kalendorf orders his people to take him to Earth to parlay with the Dalek Supreme, even Godwin hesitates to take this risk. She knows that she can’t talk Kalendorf out of his intentions, however, and agrees to give him a scoutship so he can complete the journey himself. Kalendorf pilots the ship to Earth and contacts the Dalek Supreme, who allows him to land and then locks the ship in place. It will be unable to take off from Earth again unless the Daleks allow it to do so.

Kalendorf demands to see Suz, who enters the room, apparently free to act of her own accord. But when he demands to speak to the Dalek Emperor, he finds himself still facing Suz; rather than extracting its mind from her body, the Emperor has erased all trace of Susan Mendes and taken complete control. Now the Angel of Mercy will address the people of the galaxy, claiming to be the new Dalek Emperor and promising a new era of peace... at least until the Alliance drops its guard. This is no more than Kalendorf expected, but this begs the question of why he would come to Earth knowing he was walking into a trap. Kalendorf refuses to explain; only he and Suz know the truth now, and if there really is no trace of Susan Mendes left, the Emperor will never know what Kalendorf had planned or even if he was planning anything.

Enraged, the Emperor tries to torture the truth out of Kalendorf, focussing the mental power of all Daleks in the command net through Suz’s body and into Kalendorf. But when she reaches out to touch Kalendorf, he makes telepathic contact with the remnants of Susan Mendes and reminds her of what he did on the Defiant. This is Sancroff’s strategy, the reason the traitor killed herself and her co-conspirators... because at the ceremony of Victory or Death, Sancroff planted a destructive impulse in his lieutenants’ minds, lying dormant unless the time came for him to trigger it. Kalendorf now triggers the impulse he planted in Suz’s mind, and Suz wakes to a sense of herself just long enough to carry out her instructions. Before the Dalek Supreme can stop her, Suz -- still connected to the Dalek command net via the Emperor -- sends out a destructive impulse through the net, and every single Dalek connected to it is destroyed.

This was the Great Catastrophe. When every single Dalek and piece of Dalek technology in the galaxy self-destructed, the devastation was unimaginable. Whole star systems were destroyed and countless lives were lost. And yet Kalendorf, who had always hoped to die by sacrificing his life to save others, lived through it. Somehow he struggled back to Velyshaa, where he left the legacy of his memories in the burial chamber. Now, two and a half thousand years later, his story has been told at last.