The Tomorrow People -- The Blue And The Green

John and Stephen find themselves with two mysteries to investigate - the possibility that Stephen's new teacher Elizabeth M'Bondo is a Tomorrow Person and some worryingly accurate paintings of alien planets.

John and Stephen follow Liz into hyperspace, where they manage to rescue her and return her to the lab. Convinced of their story, she agrees to help them investigate the paintings, which seem to induce violence in those around them.

John and Stephen rescue Liz from the youths and find out about the second painting. John buys it from a man who turns out to be Robert's grandfather and takes it back to the lab, only to find out it may be a trap.

John is being held prisoner by Robert in the cellar of the antique shop, unable to use his powers. Chris attempts to rescue him but only succeeds in getting himself in trouble with the police.

Robert explains to John that his race uses violent energy as a power source. If they stay on Earth, they will die, but the violence needed to power their departure will completely destroy Earth's civilisation.