In 1940 London, the parents of a 12-year-old boy are killed when their house is destroyed during the Blitz. The boy seeks shelter in a London Underground tunnel and discovers a hidden ancient tunnel, where he is almost trapped. When he emerges from the tunnel, everything looks different and he learns that it is 65 years later than when he entered the tunnel, yet he is still 12 years old. He has no parents, no friends and nowhere to go. He has to adjust to the modern world without being able to tell anyone where he comes from. The police think he's a runaway and he's put in a boarding school with uncaring staff and an oversized bully. He manages to travel to Scotland, France and Germany looking for answers. He keeps thinking about the tunnel and whether it could take him back to the world he once knew.