The story opens with the description of three little Londoners who enjoy an ordinary, peaceful life in the city with visits to the Zoo and Madame Tussauds. They have a charming, well-appointed home and loving parents. Things take a sudden turn for the worst when Father suddenly leaves after receiving mysterious “bad news.” Mother decides equally suddenly to move with the children to the country-side and here begins their adventure with the railways. They befriend a strange Old Gentleman who invariably travels on the 9.15 train from near their home and get drawn into bizarre and dangerous events…