England in the late 22nd century is slowly recovering from the devastation that followed the Dalek invasion. The Doctor's very first travelling companion – his granddaughter, Susan – is where he left her, helping to rebuild Earth for the survivors. But danger still remains all around... While searching for his lost companion, Sam, the Doctor finds himself in Domain London. But it seems that Susan is now missing too, and his efforts to find her lead to confrontation with the ambitious Lord Haldoran, who is poised to take control of southern England through all-out war. With the help of a sinister advisor, Haldoran's plans are already well advanced. Power cables have been led down a mineshaft, reactivating a mysterious old device of hideous power. But has the Dalek presence on Earth really been wiped out? Or are there still traps set for the unwary?