Railroad detective Matt Clark solves mysteries with his assistant.

Matt and Margaret investigate the kidnapping of banker Penrose from a stagecoach; they immediately suspect noted bandit Milt Sharp who recently escaped from a Nevada prison and his partner Dutch; a showdown takes place at the Penrose home.

Matt and Margaret investigate when a railroad payroll worth $25,000 is stolen.

Matt and Margaret head to Denver in the late 1860s after the killing of a railroad telegraph operator; bail jumper L H Musgrove, a known horse thief is their chief suspect; Musgrove and his pal end up facing vigilante justice.

Matt Clark and Frankie Adams pursue a female outlaw named Belle Starr after her gang steals a herd of horses from the U.S. cavalry.