Plot

Challenger experiments with a mysterious energy source, and Challenger, Roxton and Marguerite are thrown forward in time, approximately 100 years to 2033. On their return they are joined by a young woman called Finn.

Using the Plateau's mysterious energy lines as a source of power, Challenger constructs a machine to send the explorers back to London. But when he, Roxton, and Marguerite find themselves in the same place they started from, they conclude the machine is a failure and head back to the Treehouse-only to discover the Treehouse is gone. While investigating what else has changed, Roxton is captured by slavers with automatic weapons and stripped-down cars, and learns the shocking truth-he and his friends are in the year 2033, eighteen years after an apocalyptic war devastated every place on Earth except for the Plateau.

Challenger, Roxton and Marguerite are thrown through time from 1922 to 2033, where they discover a crumbling city ruled by the survivors of a catastrophic global war. They eventually escape back to their own time, joined by Finn, a young woman who may hold the key to averting the near-extinction of humanity.