Hoppy goes undercover as an outlaw (which permits him, for once, to drink and be mean to children) to track down a bunch of outlaws operating along the border. Loco, the head bad guy, deflects suspicion from himself by pretending to be a moron.

William Boyd
as Hopalong Cassidy

James Ellison
as Johnny Nelson

George 'Gabby' Hayes
as Windy Halliday

Morris Ankrum
as Loco

John Beach
as Bailey

Nora Lane
as Grace Rand

Charlene Wyatt
as Molly Rand

Trevor Bardette
as Colonel Gonzales

Earle Hodgins
as Major Stafford

Al Bridge
as Dandy Morgan