Lying in state in University College, Oxford, is the ethereal, romantic and tragic figure of Shelley, who drowned off the coast of Viareggio in 1822. The white marble statue was commissioned by his daughter-in-law, Lady Jane Shelley, as a tribute to his hallowed memory.

In A Treacherous Likeness, Lynn Shepherd tells the story of the ‘entwined and extraordinary lives’ of Mary and Percy Bysshe Shelley and her half- sister Claire Clairmont is told through the eyes of detective Charles Maddox.

We first meet him in 1850 at the home of his great uncle and mentor, who has just suffered a stroke on seeing a calling card summoning Charles to visit the elderly and frail Mary Shelley, her son Sir Percy and his dominating wife Jane, who controls Shelley’s archive.

On entering their living room, Maddox is faced with a shrine to the poet. His orders are to retrieve any documents Claire may be harbouring; he soon realises their sole aim is to protect, enhance and sanitise the name of the great poet.

As he delves into the scandals surrounding the Shelleys he discovers, to his dismay, that concealed papers belonging to his revered great uncle, the most able and trusted thief-taker of his day, reveal his involvement with the poet, his women and children in 1814.

The Oxford author’s sense of Dickensian London intensifies the horror of her melodramatic whodunnit, with its fogs, swirling leaves, smells, poverty, infant deaths, adultery and secrets. Her original vision and ample research bring to life a lost world, leaving us wondering to what extent art can enrich reality. Her stated aim: to fill the ‘strong silences and inexplicable gaps’ in the lives and loves of these Young Romantics, known as much for their radical ideals and scandalous sexuality as for their writing.

Rather than highlighting the episode in Lake Geneva when Percy and Mary Shelley, Claire and Byron told one another frightening stories — the most famous being Mary’s Frankenstein — Shepherd focuses on the death of Shelley’s first wife Harriet in mysterious circumstances.

None of her strong cast of characters, not even narrator Charles, comes out well, but all are evoked with skill and sensitivity in this gripping story.