Who are the "green men" and why are bad guys willing to kill to get them?

Original Air Date: November 10, 1951
Host: Andrew Rhynes
Show: Hopalong Cassidy
Phone: (707) 98 OTRDW (6-8739)

Stars:
• William Boyd (Hopalong Cassidy)
• Andy Clyde (California Carlson)

Writer:
• Herb Perdum

Creator:
• Clarence Mulford

Producer:
• Walter White Jr.

Music:
• Albert Glaser

Exit music from: Roundup on the Prairie by Aaron Kenny https://bit.ly/3kTj0kK