Quarantines, masks, death—terms familiar to anyone who faced the so-called Spanish flu of 1918. Worldwide, it is estimated that the horrifying influenza killed more than 50 million people, significantly more than did the guns of the Great War, which was just then coming to a close. And yet no one has ever heard from Sherlock Holmes or Dr. Watson concerning their own experiences surviving the terrible virus—until now.

In a recently discovered manuscript, Dr. Watson reveals the secret that for years had kept him silent about the deadly pandemic. Only when he meets the eccentric American novelist Sinclair Lewis is the truth pried free and the story of an ingenious murder revealed.