It is the early summer of 1379 and Sir John Cranston—Coroner of the city of London—has trapped himself in a wager with Signior Gian Galeazzo, Lord of Cremona, who has challenged him to resolve a certain murder mystery within two weeks. Men have been repeatedly found dead in the scarlet chamber of one of Cremona’s manors. They have no marks upon them, they have neither drunk nor eaten poison, and there are no secret passageways or entrances to the room. They are united only by the have awful expressions of terror upon their faces. Realizing that his reputation and future wealth now rest upon the solving of this mystery, Cranston seeks the help of his faithful secretarius Brother Athelstan in untangling the perplexing case.