As ghosts go, Maria Vaduva, who haunts Enlightenment, is not a patch on the wild, tormented figure who stalks the pages of Sarah Perry’s previous novel, Melmoth. Where Melmoth, in rage and despair, haunts everyone complicit in history’s horrors, Maria is crossly plaintive. The disappearance of this unrecognised 19th-century Romanian astronomer from Lowlands House, a manor in the fictional small Essex town of Aldleigh (where marriage has brought her), becomes the obsession of Thomas Hart.