An evil gang is involved in both cattle rustling and the robbing of stagecoaches. Hoppy must stop them without help from the sheriff who turns out be a major outlaw himself.

Gun moll Nan Taylor, caught after an otherwise successful bank robbery, falls for radio crusader David Slade and confides her guilt to him. Much to her surprise, he turns her in. As a "new fish" at San Quentin, Nan fits right in, but won't see Slade, who still loves her. Then she learns that her former partners in crime, Don and Dutch, are on the other side of the wall in the men's section...and have an escape plan.