 Dan Mathews gives a lift to Dr. Leonard, who is en route to the home of rancher Fred Bell. The doctor finds that Bell s 10-year-old son Johnny has gas gangrene and needs life-saving serum as quickly as possible. The serum must be delivered by air from a distant city and Bell s foreman Marty Gower offers to help Dan find his way to retrieve the serum from the airport over the rough back roads. Dan returns to the Bell household, but he bears injuries from an automobile accident and both the serum and Marty are missing. Marty was having financial problems and Dan suspects that he may have caused the accident deliberately so he could hold the serum for "ransom". Dan and Officer Abel backtrack from the location of the accident and discover that things are not always as they seem.