The Railway Children (Illustrated, with Audiobook links) (E. Nesbit 4)

Edith Nesbit’s classic story, in which three children, pulled suddenly from their comfortable suburban life, move to the country with their mother, where they come to know and love the ways of the railways. This kindle version is illustrated, and even includes a free audiobook link!

Summary:
The story concerns a family who move to "Three Chimneys", a house near the railway, after the father, who works at the Foreign office, is imprisoned after being falsely accused of spying. The children befriend an Old Gentleman who regularly takes the 9:15 train near their home; he is eventually able to help prove their father's innocence, and the family is reunited. The family take care of a Russian exile, Mr Szczepansky, who came to England looking for his family (later located) and Jim, the grandson of the Old Gentleman, who suffers a broken leg in a tunnel.