A famous (if scandalous) female detective and her secretary (a woman disguised as a young man) solve a case involving murder and the black-market sale of illegal scientifiction during New Ceres's twelve-day Feast of Saturn (based on Earth Christmas).
As the author acknowledges at the beginning of the story, the plot is loosely adapted from Agatha Christie's short story 'The Adventure of the Christmas Pudding' (from The Adventure of the Christmas Pudding and a Selection of Entrées, 1960).