When young chimney sweep Absalom 'Barnacle' Brown stumbles upon a dangerous conspiracy among London’s Victorian elite, he becomes the target of the menacing Inspector Creaker. Fleeing to the safety of a Thames barge, The Lady, under the care of kindly skipper Tom Gosling, Barnacle adapts to life on the river and befriends the formidable Mrs McDipper and her daughter Miranda. As Creaker’s gang closes in and a mysterious foreign vessel, The December Rose, docks with a perilous secret aboard, the story builds to a feverish climax in which Barnacle and his allies confront evil head‑on.