Mark Trail, the main character, is a photojournalist and outdoor magazine writer whose assignments lead him into
danger and adventure. His assignments inevitably lead him to discover environmental misdeeds, most often solved with a crushing right cross.
Trail lives in the fictional Lost Forest National Forest with his St. Bernard, Andy; veterinarian Doc Davis; Doc's daughter, and Trail's
girlfriend and eventual wife, Cherry, and their adopted son, Rusty. "Mark reflects a reverence for God's creatures, nature, and the conservation
of woods, water and wildlife" (Hill, 2003). His assignments in recent years have involved more sleuthing than wildlife photojournalism.
On January 30, 1950, Mutual Broadcasting System launched a radio adaptation, Mark Trail, featuring Matt Crowley in the
title role. The 30-minute episodes aired three times weekly, and 174 episodes were produced, running until June 8, 1951. A second radio series, starring
Staats Cotsworth, was broadcast on ABC beginning September 18, 1950, with 51 half-hour shows that ran thrice weekly until January, 1952. The series then
switched to a 15-minute format, producing 125 episodes that aired weekdays through June 27, 1952. Only a handful of the 15-minute episodes are known to have survived.