What happens
Hopalong Cassidy, foreman of the Bar-20 Ranch, rides to Judge Marlin's spread in Arizona after the judge asks for help with trouble on his land. Cassidy, Johnny and California find the judge's cattle vanishing along a trail that ends at a waterfall. Cassidy and his companions follow the herd's tracks and find a hidden canyon behind the falls, where the stolen cattle are kept. The series, this broadcast's original air date of August 11, 1941, and its lead actors are not stated in the transcript, so they are omitted here.
Arizona ranch country near Twin Forks and Stoney Creek, including a saloon, the judge's ranch and a hidden canyon behind a waterfall
Characters: Hopalong Cassidy, Johnny Nelson, California, Buck Peters, Judge Marlin, Myra Marlin, Dan Marlin, Clark Crandall
Listen for: Cassidy and his companions finding the hidden canyon behind the waterfall, and the tunnel escape
Written from the episode itself; it never gives away the ending. Every recording is remastered for the stream: cleaned of rumble, hiss and mains hum (and the old TV whine where we found it), then levelled in two passes to steady broadcast loudness, so one show is never quieter than the next.