What if the dead could sit for their portrait?

London, 1889. When Mrs. Viola Marston brings three seemingly ordinary photographs to 221B Baker Street, she presents Sherlock Holmes with a case like no other. In each portrait—taken weeks apart, in different rooms, by a reputable studio—a veiled woman in mourning dress stands at the edge of the frame. No one present recalls seeing her. No one can explain how she appeared on the glass plates. And when Mrs. Marston’s brother, Felix Dane, recognises the spectral figure and whispers a name he has not spoken in years, he vanishes into the London fog.

Holmes and Watson are drawn into a web of deception that stretches from the elegant portrait studios of Regent Street to the fog-shrouded warehouses of Limehouse—and into the buried history of a woman destroyed by the very family now haunted by her image. What they uncover is not a ghost, but something far more unsettling: a grieving man of extraordinary skill who has turned the camera’s claim to truth into a weapon of conscience.

At stake is more than one man’s freedom. It is the question Holmes finds most difficult to resolve: what does justice look like when the law has no answer, and the guilty walk free?

A richly atmospheric mystery of photographic illusion, Victorian social injustice, and the riddle that only the great detective can solve—not with logic alone, but with something rarer still: moral reckoning.