Major characters:
Madeline Gray, who seeks out The Saint
Calvin Gray, her inventor father
Frank Imberline, WPB (War Production Board)
Sylvester Angert, a funny little man
Hobart Quennel, head of Quenco Chemical
Andrea Quennel, his daughter; a.k.a. Diana Barry
Walter Devan, personnel manager of Quenco Chemical
Karl Morgen, a tough
Simon Templar, The Saint
Inspector John Fernack, of the police
Locale: Washington, New York, and Conneticut
Synopsis: World War II is in progress. Simon Templar is in Washington. A young Madeline Gray recognizes him and seeks his help. She is the daughter of chemist Calvin Gray, and is trying to interest the Washington bureaucrats in her father's invention: a synthetic rubber; which would be invaluable for the war effort.
She sets up an appointment with Frank Imberline of the War Production Board. Then she is warned off from seeing him. Simon visits Imberline to find he was unaware of the appointment. Suddenly various actors start having an interest in Madeline: Walter Devan of Quenco Chemical, and Sylvester Angert, a funny little man who listens at her hotel room keyhole. Someone shoots through the window of Simon's hotel room.
Simon wants to check out Calvin's Gray's process. He and Madeline travel to her home in Connecticut, to find Calvin apparently missing. Madeline sees a man lurking in the lab, and recognizes him as Calvin's former employee, Karl Morgen. Simon challenges him. Morgen flees. Simon chases, and trips over the body of Sylvester Angert.
Review: This, being one of the early Saint stories, is when he is in his early tough-guy persona, which may have played well in the movies, but is a bit too hard-boiled. (He even refers to the actor who plays him in the movies!) He tends to hit or shoot first, not the subtle Saint we like so much later on. Plus, this is set in the US which is not his best venue.
I really prefer those set in the UK when he has Patricia Holm at his side, and matches wits with Claude Eustace Teal.
Other than that, we have the stock bad-guys-after-the-scientist plot, complete with the beautiful daughter in distress. Overall, quite predictable with a lot of World War II era paranoia stirred in.