Yembe burnt the facility to the ground, but spared a single baby whom he and Francine adopted. The Doctor, Kadiatu and Blondie return the Doctor's house on Allen Road in Kent. While Kadiatu and Blondie make love, the Doctor constructs a device for hacking into the tunnel network. The Doctor deduces that the intelligence invading the tunnels is from another dimension and operates similarly to a computer virus using a neural computer system. He also learns that the STS system has become self-aware, and communicates with it via a hologram of television anchorman, Yak Harris. The hologram confirms the Doctor's theory, which they then report to the STS executives in London. At the same time, the Floozies identify an energy build up, indicating that the hole between dimensions is about to open again. On Mars, Benny has gained access to the STS system, but the controlling influence weakens as she gets further from the tunnels. She recovers enough to send Zamina to the Doctor for help. The Doctor and Kadiatu arrive on Mars, in time to see Benny fleeing from the human colony, killing anyone in her way. They follow, and corner her in an Ice Warrior nest. Benny reveals a gun and Kadiatu shoots her. As the sleeping warriors begin to revive, the Doctor realises that this "Benny" is a duplicate created to distract him. Kadiatu summons Francine to fly them back to the settlement. En route, the craft accidentally activates a missile defence system, but Francine's manages to land the craft. Another duplicate of Benny enters a STS reactor and overloads the power, creating enough energy to open the breach. The Doctor sends the Floozies to the end of the line to build a machine to his specifications and connected to the TARDIS. The group—including Benny, who is disguised as one of the station's staff—come under attack by the mutant creatures, and Blondie is among the fatalities. The Doctor commandeers a freesurf board and heads through the tunnels to the station, picking up a piece of software hitch-hiking in the system along the way. Barely surviving the landing, the Doctor sees the breach open. The virus was an agent laying the groundwork for the real invader to emerge—it is nameless, but the Doctor calls it Fred. The Doctor uses the machine to fire a burst of artron energy from the TARDIS. Fred retreats through the breach, taking Benny