Sir Gerald Tarrant, head of a secret service department in the British Government, and good friend of Modesty Blaise, is being driven by his chauffeur along a narrow road on the edge of the gorge of the Tarn River in S. France.

Modesty and Willie Garvin have by chance already determined the probable location of Sir Gerald's captivity: Chateau Lancieux in the foothills of the Pyrenees in S. France.

Modesty and Willie gain access to the chateaux via a deep cave, but on entering into the basement they are captured by the formidable Mr. Sexton, who prides himself on being the world's greatest unarmed combat man.

Now Modesty and Willie are scheduled to die at Mr. Sexton's hand, one at a time, to further the process of softening Sir Gerald up for interrogation.

Modesty Blaise Willie Garvin Sir Gerald Tarrant Henry Quinn Lady Janet Gilliam Colonel Jim Straik Mr. Sexton Angelica "Angel" Clare McTurk Lucy Straik René Vaubois Weng The Silver Mistress was broadcast as a five-episode adaptation on BBC Radio 4 from February 13-17 2017, adapted by Stef Penney and directed by Kate McAll, featuring Daphne Alexander as Modesty, Paul Bazely as Willie and Ian McNeice as Tarrant, with Clare Grogan (Clare), Ewan Bailey (Sexton/Colonel Jim), Sara Markland (Lady Janet/Angel) and John Ramm (Quinn).