It is six months since Greg, Agnes and Jack left Whitecross. Seth finds Jack wandering in a fever in some woods and takes him back to his home to look after him. There finds that Jack has letters for Charles and Jenny which are from Greg. Charles, Pet, Jenny, Hubert and the children have moved from Whitecross to Challoner. When they learn the news about the letters, Jenny and Charles go to Seth's home. Jack is delirious and says some unintelligible things about a place called Wellingham, where he and Greg had been. A distraught Jenny is desperate to see Greg again, so she and Charles head off to Wellingham. Pet also sends Hubert on after them. After rescuing a man staked out in the woods and meeting the authoritarian Clifford and the sinister Miedel, Jenny and Charles become worried about the situation in which they have become embroiled...

Charles, Hubert and Jenny are reunited with Agnes, who has become separated from Greg. They visit the Walter's family farm, where Greg and Agnes met Tom Walter and his family some months ago. However, the farm is deserted as Tom' mother, Edith, and her sons Steve and Owen were driven from it, when Tom was away, by former butcher Brod, to a camp by a railway line. Charles, Jenny, Agnes and Hubert are captured and taken there as well. Brod has special plans for Jenny and sees Charles as a threat to his position...

Charles, Jenny, Hubert, Frank and Alec arrive at a settlement based at an old coal mine. The settlement's leader, Leonard Woollen, is anxious to get the mining equipment working again and enlists Alec and Charles's help. Another man, Sam Mead (Robert Gillespie) is opposed to the idea fearing a return to the age before 'the death'. Jenny is becoming increasingly emotional about the absent Greg. Charles pushes her too far in relation to Alec...

Greg is looking for a Dr.Adams who he thinks is being held captive. He is attacked by four men who steal all his notes on the settlements he has visited. He survives the encounter but runs into further danger when he finds Dr.Adams, who has contracted smallpox. Greg must now wait until the incubation period is over to see if he has contracted the disease...