Scotland, 1932. Aristocratic private investigator Dandy Gilver strikes again with her witty sidekick Alec Osbourne to solve sinister goings on at a convent on a bleak Lanarkshire moor. The convent was set alight following a mass breakout at a neighbouring psychiatric hospital on Christmas Eve, resulting in the death of the mother superior. Most patients were returned safely but a few are still at large. . . As Dandy interviews each nun in turn she senses a stranger is still lurking in the corridors at night - could they be the same person who left blood-red footprints in the sacristy? One of Catriona McPherson's creepiest - and funniest - mysteries yet.