Escape's "The Footprint" was adapted from a 1908 short story by Gouverneur Morris (1876-1953), a pulp fiction author who was the great grandson of American founding father Gouverneur Morris (1752-1816).
Escape probably chose this particular adventure story for radio because it involves a small, menacing snake, and to them, any story about a snake was a good story. That is true of "Poison,""Serenade for a Cobra" and "A Shipment of Mute Fate," but "The Footprint" falls short. The original work, which is available online at Google Books, contains all of the elements for a great Escape episode--but that didn't happen.
As the episode opens, a group of men set sail from San Francisco to northern Mexico. They have banded together because of a treasure map they hope will direct them to a hidden fortune in rubies. When they arrive at their destination in the Gulf of California, they find another ship is there as well. They watch as a fat Chinese man with a yellow parasol leaves the ship and then begins to walk across the desert.
The men follow his footprints and eventually, catch up to him. The man, Sang-Ti is on his way to the hidden outpost of Chen Chan because it has been prearranged that his life will end there. Sang-Ti warns them to turn back, but the men say they can't. They have come too far. Sang-Ti also warns them not to steal the holy ruby box-- but they do. When the men try to return to their ship, they are pursued across the desert by a strange priest wielding a nasty little snake.
"The Footprint" was adapted for radio by Richard Chandlee and produced/directed by Norman MacDonnell. Featured in the cast were William Conrad, Charles Davis, Lou Krugman, Tom Holland, and Ramsay Hill. This episode aired on August 18, 1950.
(Image of Gouverneur Morris in his study from Google Books)