The Boy Who Turned Yellow

John (Mark Dightam) loses one of his pet mice, Alice, whilst on a school trip to the Tower of London. Later that day on the London Underground, the train and everyone in it suddenly turns bright, vivid yellow. John's doctor declares that the condition is harmless and should wear off soon, but that evening John hears noises from his television set and meets the eccentric yellow-coloured Nick (short for Electronic) Nick. The pair return to London in an attempt to find Alice, but they are menaced by Yeoman Warders.