Approximately month fourteen. Ben is now a member of the family group, but David is concerned that he and Joanna are becoming very close. He tries various means to keep them apart, despite Elizabeth's view that the more he tries , the more the young couple will seek to see each other. Billy and Christina are trying to secretly build a raft to explore a nearby river, but David's insistence on them doing school lessons is hampering their progress. Billy tricks Emily into doing the schoolwork for them and the raft progresses. When Billy overhears Ben declaring his love to Joanna, he foolishly tells Christina, who lets it slip at the family dinner table. David is outraged and a confrontation occurs between the father and the young lovestruck youth. Banished from the compound, Ben goes to live in a cave. Billy and Christina's raft voyage is cut short when it falls apart. Having gained dry land the youngsters are confronted by a large wild dog. Ben rescues them and takes them safely home. David is grateful but still cool. Ben comes to Joanna at night and persuades her to leave with him. David sets off in furious pursuit to Ben's cave. Joanna is on her own when she hears her father coming. She retreats into the maze of tunnels leading from the cave and gets lost. Ben and David meet, each convinced that the other has spirited Joanna away. Realising that Joanna is in the tunnel maze, the two antagonists go in search of her. At the tree house Elizabeth starts to give birth. Emily is forced to act as midwife. Joanna is attacked by the wild dog in the tunnels but is rescued by David and Ben. As they emerge they see a ship on the horizon. Ernst is despatched to light the beacon. David and Ben return home to find the baby well, but Elizabeth has a fever. Emily learns of the ship and secretly puts out the beacon.
