The year is 1757. On a clear morning in mid-June, Lord John Grey emerges from London’s Beefsteak Club, his mind in turmoil. A nobleman and a high-ranking officer in His Majesty’s army, Grey has just witnessed something shocking. But his efforts to avoid a scandal that might destroy his family are interrupted by something still more urgent: The Crown appoints him to investigate the brutal murder of a comrade-in-arms who may have been a traitor. Obliged to pursue two inquiries at once, Major Grey finds himself ensnared in a web of treachery and betrayal that touches every stratum of English society—and threatens all he holds dear. From the bawdy houses of London’s night world to the stately drawing rooms of the nobility, Lord John pursues the elusive trails of a vanishing footman and a woman in green velvet, who may hold the key to everything—or nothing.