Joe Ryan, a veteran train engineer, is demoted to a flagman position after a disastrous crash-- one caused by his cowardly and opportunistic partner. Though Ryan's failing eyesight is named as the cause of the crash, he's undeterred as he designs an automatic braking invention.

When the Government incorporates Bill Hayden's ranch into a Federal game preserve, Jack McCabe, a forest ranger, is sent to serve an eviction notice on Hayden and his daughter, Shasta. Hayden resists the order, and Jack falls in love with Shasta.