In this fifth adventure of Cyrus Skeen, private detective and socialite in San Francisco, it is January 1930, the end of the Roaring Twenties and the beginning of the "Red Decade" when Soviet spies and Communist fellow travelers have begun to infiltrate the government and other institutions in large numbers.

During a Nob Hill society party, Skeen and his painter wife, Dilys, befriend a beautiful sculptress who turns out to be a British spy carrying important information about the extent of that infiltration in American and British governments.

In A Crimson Overture, one thing leads to another, and soon Skeen is enmeshed in a conspiracy to silence him and anyone else with knowledge of the scale of espionage and treason in both countries.

In the previous Skeen case, The Chameleon, the intrepid and cosmopolitan detective uncovers and dissolves a Nazi Bund in a university town near San Francisco, while in The Daed'lus Conspiracy, he journeys north to a Redwood Forest to foil the assassination of a U.S. Senator.

In this latest exploit, Skeen tangles with J. Edgar Hoover's Bureau of Investigation, irascible police detectives and newspapermen, and ruthless Soviet agents hurrying to cover up their depredations before the British spy's secrets are revealed to the authorities.