Plot

Charles, Hubert and Jenny take the steam train up to Scotland, where they plan to meet with Alec and Sam after electricity has been restored. But none of them have realised that Sam's plan all along was to sabotage it.

Travelling to a hydro-electric power station in Scotland, Charles, Jenny, and Hubert meet a local laird, who tells them that in the Highlands more than 150,000 people have survived the plague, making it the most densely populated part of Britain. Charles informs him that they are there to switch the electricity back on, which Alec and Sam are now working on. At the power station, Alec is making preparations, but Sam is sabotaging Alec's work. The others arrive there to find Alec unconscious, while Sam has disappeared, intent on wrecking the whole system. During a struggle, Sam is killed. Before the supply is restored, the Laird argues with Charles that the power belongs to Scotland, but Alec insists that he is the only one able to switch it back on. After they reach an agreement that Alec will control the supply, Alec switches it on.—GusF