and meets two prostitutes, Zamina and Roberta. Unknown to Benny, Roberta is a childhood lover of Blondie who resents him for escaping the slum. Roberta has Kadiatu's moneypin, which she took after having seen her and Blondie making love. Behiaving strangely, Benny demands to be taken to a local gang leader, whom she then encourages to take over the slum. Violence spreads across the slum, killing many including Roberta and eventually leading to military intervention and evacuation of the survivors. The Doctor awakens in Kadiatu's room at the Lunarversity and, looking through her belongings, realises she has been researching his visits to Earth and that she was genetically engineered. He also discovers that she is close to developing a time machine. Unsure how to act, the Doctor first solves Kadiatu's problem with the drug dealers and then searches for Benny, stowing away on a maintenance train heading to the relief zone on Pluto. A mysterious train-shaped object begins moving through the tunnels, swallowing passengers and pirate free-surfers (who use special boards to traverse the tunnels illegally). Its victims are re-engineered into mutant soldiers to serve the intelligence that has invaded the tunnels. Francine contacts Old Sam about Blondie, but he convinces them that he knows nothing about the moneypin. Using the tunnel surveillance system, they locate Kadiatu and the Doctor heading for Pluto. Old Sam and Blondie set off to investigate, intending to rescue Kadiatu. The Doctor finds the TARDIS embedded in a concrete wall at the end of the line. While the Doctor tries to work out a way to free it, the pair are attacked by Benny. The intelligence has possessed her, but it does not recognise the Doctor as a threat. Kadiatu realises that her instinctive response to danger is to kill, and that her punches are capable of causing fatal injuries. Old Sam and Blondie arrive and Benny escapes, joining Zamina on a refugee train heading for Mars. Zamina realises that Benny caused the riots for just this purpose. Flashbacks reveal that Kadiatu's father, Yembe, is a descendant of Alistair Lethbridge-Stewart and an African woman with whom he had a brief relationship during his service in Africa. Years later Yembe Lethbridge-Stewart had been a soldier in the war against the Martians, where he met Francine. After the war, Francine learnt from a mysterious hacker that a facility outside Leipzig was being used to genetically engineer super-soldiers.