Escape's "Confidential Agent" was adapted from the 1939 novel The Confidential Agent: An Entertainment by Graham Greene. In this instance, they chose not to adapt the book as it was written, and so changed the story and characters that there is little resemblance between the radio version and the source work. The question is...why? The novel (which Greene wrote with the help of benzedrine) is the sort of desperate, gritty story that Escape normally didn't shy away from.
Was it because Greene's novel about a middle-aged, traumatized, war-weary, beaten-down agent who is relentlessly pursued by enemies and police--was just too depressing? Probably. Escape, instead, chose to punch up the excitement by making the agent younger, the story less perilous, and the romance standardized.
Escape's adaptation was written by a man named Kendall Foster Crossen (1910-1981). Crossen was a prolific radio script writer, pulp fiction writer and an editor of Detective Fiction Weekly. He wrote more than twenty novels featuring Milo March, an insurance investigator.
So, Escape's "Confidential Agent" is really a radio play by Kendall Foster Crossen within the basic framework of Greene's novel.
Confidential Agent was also made into a movie in 1945 by Warner Brothers. You can find a review of both the novel and the movie over at Mysteryfile.com.
As the episode opens, a boat has just arrived in Dover harbor. David, a secret government agent, has come to England on a mission to obtain industrial diamonds. He is suspicious of everyone, but when fellow passenger Rose Cullen offers him a ride from Dover Harbor to London, he accepts. Is she one of them? Will the two of them make it to London without trouble? If they can, will David be successful in his mission?
"Confidential Agent" was adapted for radio by Ken Crossen with editorial supervision by John Dunkel. Norman MacDonnell produced and directed. Berry Kroeger starred as D. Also appearing were Edgar Barrier, Constance Cavendish, Herb Butterfield, Parley Baer, Olive Deering, Ben Wright, Wilms Herbert and Alec Harford. This episode aired on April 2, 1949.
(Image of Kendall Foster Crossen from Wikipedia)