The Doctor begins to work on a cure. Masters has reached London and eludes the search parties looking for him. The bacteria spreads, and deaths begin. The Doctor finds a cure, but the Silurians attack the centre and abduct him. Liz discovers the formula for the cure, which is soon mass-produced and distributed. The Silurians intend to force the Doctor to use the reactor to provide power to a weapon to destroy the Van Allen Belt and make the Earth's environment hostile to humankind.