For very-nearly-eleven-year-old Flavia de Luce, the discovery of a dead snipe on the doorstep of Buckshaw, the crumbling de Luce country seat, was a marvellous mystery - especially since this particular snipe had a rather rare stamp neatly impaled on its beak. Even more astonishing was the effect of the dead bird on her stamp-collector father, who appeared to be genuinely frightened.
Soon Flavia discovers something even more shocking in the cucumber patch and it's clear that the snipe was a bird of very ill omen indeed. As the police descend on Buckshaw, Flavia decides it is up to her to piece together the clues and solve the puzzle. Who was the man she heard her father arguing with? What was the snipe doing in England at all? Who or what is the Ulster Avenger? And, most peculiar of all, who took a slice of Mrs Mullet's unspeakable custard pie that had been cooling by the window...?