Five-year-old John Maltravers has been left under the guardianship of his uncle and aunt, whilst his father, Edward, is soldiering abroad.

Believing Edward to be dead, and hoping to inherit the wealthy Surrey Malltravers estate instead of John, the treacherous uncle and aunt plot his abduction, and John finds himself forced into a new life as a chimney sweep. Untrained, and unsupervised, he suffers a nasty fall, but is rescued by the Forester family. Widowed Caroline becomes his great ally, and the family are determined to help John trace his relatives.

However, tormented by the family's younger children, John runs off to wander the streets and alleys of Georgian London, seeking his father. In turn, Edward Maltravers, newly returned from India, is searching for his son.

John faces the perils of criminal-haunted London streets, wandering into the notorious slum tenements of St Giles, and encountering many a character, some more well-meaning than others.

This is a story of hope over adversity, the victory of innocence over guile and treachery. Will John ever be reunited with his father and beloved Caroline? If so, how?