The Thousand Worlds ( audio story ) Publisher ' s summary . With the high - ranking Time Lord Seratrix behind enemy lines , the War Doctor finds himself assigned to a rescue mission . But any room for manoeuvre is severely restricted by an area of space known as the Null Zone . Times have changed on Keska , and a countdown to destruction is beginning . But who are the Taalyens and what is their part in the great and terrifying Dalek plan ? Plot . After the Doctor ' s extraction from Keska , Rejoice meets with her father , and tells him that the Doctor is gone . She mourns his loss , but her father is glad she was left behind . From the Doctor ' s perspective , the story continues immediately . He meets with Cardinal Ollistra , who orders him onto a strike team led by Veklin , the agent who came for him on Keska . Also on the team are Bennus and Arverton , the two agents whom the Doctor rescued from the Time Destructor before landing on Keska . Ollistra wants them to go behind enemy lines — that is , into an area of space called the Null Zone , which is held by the Daleks . The area is so called because time travel is impossible inside it ; only spaceflight can be completed . They will be looking for a missing Time Lord strategist named Seratrix . The Doctor — who still declines to be called by that name — insults Ollistra and Veklin , then summons his TARDIS and escapes , refusing to be part of any team . Veklin , Bennus , and Arverton follow him in a Battle TARDIS . Meanwhile , the Daleks are preparing to execute their plan . The Doctor hits the border of the Null Zone , and is forced to land on Keska , although he doesn ' t know that ' s where he is . He finds himself in a slave camp , and meets a man named Garv , who informs him of the planet ' s identity , leaving him stunned . The Taalyens have somehow conquered the planet ; and now , a massive drilling machine is being built . But why ? And how ? Moreover , there are a thousand worlds in the Null Zone , and all of them have received the same treatment . Meanwhile , Veklin ' s team also lands , though not nearby , and finds several life signs : Keskan , Taalyen , Gallifreyan … and Dalek . The Doctor promises Garv that he has fought the Daleks before , and will defeat them here . When asked for a name , he calls himself John Smith . He is separated from Garv ' s slave group , who are sent down to the drill level . The Daleks mention a pre - launch sequence , sparking the Doctor ' s curiosity . Veklin and her team pursue the Doctor — and , hopefully , Seratrix — into the machinery , carrying demolition packs . The Doctor meets a Taalyen guard , and passes himself off as a slave elite . The guard challenges him , but he is saved by a real slave elite , the woman in charge of that group of slaves . Once free of the guard , she becomes emotional , because she recognises the Doctor , though he does not recognise her at first … it is Rejoice . They bring each other up to date , but Rejoice thinks he cannot save the planet this time , as the Daleks are supporting the Taalyens — in fact , it was the Daleks who helped them get inside the planetary shield . The Doctor assures her that there is a connection between the situation here in the thousand worlds and the greater Time War . . . and he intends to figure it out . Veklin ' s team infiltrates via the fuel - pumping tunnels of the machinery , but they must hurry ; periodically , fuel is purged through the tunnels , and will kill them . They are detected by the Daleks , who send a Taalyen squad in after them . They defeat the squad , but are caught by a fuel purge ; Arverton sacrifices himself to get them to safety . He refers to Bennus in his last moments as " brother " ; this piques Veklin ' s curiosity . Bennus attributes it to a unit they served in , under Seratrix and Ollistra . Meanwhile , the Daleks think they were all killed in the purge . The Doctor and Rejoice help serve food at a celebratory feast for the Taalyen leadership ; the Prime Dalek is also there , with the Taalyen commander , Traanus . Seratrix is also there ; the Doctor learns , to his horror , that Seratrix is working with Traanus and the Prime Dalek . He is outed as a Gallifreyan , but Seratrix vouches for him and saves his life ; he knows that if the Daleks recognise him as the Doctor , they will kill him . The drilling machine is launched . It will drill into the planet ' s core , and destroy the core ; it ' s a plan the Doctor has seen before . Seratrix insists that he is working for the greater good ; this plan will lead to peace with the Daleks , who now rule the Null Zone . The Doctor is shocked to silence , as the Daleks chant , " Peace in our time " .