Peter Carey has constructed a labyrinth. Let me gropingly try to lead you through it. The year is 1837. A convict, transported to New South Wales for the term of his natural life, returns to London intent on finding the boy who years before did him a kindness. The boy, Henry Phipps, has grown up a gentleman, thanks to the money the convict, Jack Maggs, has regularly remitted from the colony. Now Maggs comes back in person, unlawfully, wanting recognition from Phipps, whom he regards as a son. He is determined to deliver his history, his own sorry apologia, written in mirror-writing and invisible ink, at the heart of which is the secret memory of an innocent girl hung by the law.

The novel’s story begins with Maggs’s disguising himself as a footman in the eccentric establishment of Percy Buckle, bookloving fishmonger turned sham gent by another unlikely windfall. Here are more stories – of the maid, Mercy, Buckle’s young mistress, who falls for Maggs; and Constable, the other footman, rogered by the dashing Phipps, who lives across the street but is hiding out in his club; and the novelist, Tobias Oates, who comes to dinner and applies his skill with mesmerism to hypnotise the phoney footman, Maggs. It’s explained as a kind of psychotherapy in which the demons of the mind will be released. Mesmerised, Maggs takes off his shirt to reveal the scars of the lash across his back. To the terrified onlookers, he becomes a monster in their midst. For the writer, Tobias Oates, he is a case study of the criminal mind and extraordinary raw material for a novel. Thus Maggs’ inner and outer stories entwine with the novelist’s own.

When he entered the soul of Jack Maggs, it was as if he had entered the guts of a huge and haunted engine. He might not yet know where he was, or what he knew, but he felt the power of that troubled mind like a great wind rushing through a broken window pane.