After their father is mysteriously forced to leave home, the three children and their mother leave their comfortable house in London and go to live in a cottage in the country near a railway track. The children soon make friends with the Station Master, the Porter and a friendly old gentleman, who waves to them from the morning train. Peter, Bobbie and Phyllis enjoy several exciting adventures and even become the heroes of the village. But the mystery of their father remains unsolved, until one day...