The book starts out at Peter’s birthday, when he receives a toy railway engine. His engine gets blown up, and as the children’s father sees the about getting the engine fixed, he is called away on business. Suddenly, the children have to move, coming by railway to a station not far from their new house, called three chimneys. They go to their house and spend the first few days getting settled in. A couple of days later is a cold rainy day, but mother says they can’t light a fire, so Peter takes some coal from the station, calling it “mining” as he took it from the center of the pile. The station master scolded him for it, but they eventually made it up and became good friends. After this they also made the acquaintance of Perks, the porter. There is one man who is always on the train, and they wave to him each morning as the train comes by. They end up asking him for help when their mother gets sick and they can’t afford the things she needs. Then, Roberta, or Bobbie, Peter’s older sister, decides to see if an engineer can get Peter’s train fixed. She succeeds, and after that, they meet a gentleman who speaks French and they learn that he is an escaped Russian prisoner, and is looking for his family. After getting some new from the Old Gentleman’s Russian friends, he finds them. Before the Russian Gentleman leaves, they go to the railroad cutting to get him some flowers, but as they are there, a landslide ‘happens’ blocking off the rail. A train is coming, and they are able to save it by making flags and waving them. Not long after this, Peter decides to go fishing in a near by canal, but a man on a barge stops him. After that, the barge gets set on fire, and they are able to rescue a dog and a baby. After that, they bring gifts from people around town to Perks for his birthday. In the next chapter, Roberta learns the secret of why their father disappeared by looking at some newspapers Perks gave Peter to read after he hurt his foot. In the next three chapters, Roberta, Peter, and Phyllis find a boy in the railroad tunnel and take him home. His father turns out to be the Old Gentleman. The Old Gentleman is able to help find their father (somehow) and Roberta goes to the station and is able to meet him.