A story of the Michigan State Police and the strong sense of loyalty and duty it instills in its men. It follows the career of a newly-inducted rookie, Ross Martin, who has joined the force at the urging of his sweetheart, Mary Adams. Martin soon distinguishes himself by his bravery in the apprehension of criminals. But when the leader of a gang of bank robbers falls into his hands and then escapes, because of carelessness on Martin's part, he is suspended from the force.
| Actor | Role |
|---|---|
 Fred MacMurrayTrooper Ross Martin | Trooper Ross Martin |
 Ann SheridanMary Adams | Mary Adams |
 Guy StandingJohn Vilker, alias Prof. Anthony | John Vilker, alias Prof. Anthony |
 Marina KoshetzNan Vilker | Nan Vilker |
 Dean JaggerTrooper Jim Burton | Trooper Jim Burton |
 William FrawleyTraining Sgt. Barrel | Training Sgt. Barrel |
 Frank CravenSheriff Peter Arnot | Sheriff Peter Arnot |
 Nora CecilGranny Adams | Granny Adams |
 Charles Cahill WilsonTrooper Captain Ryan | Trooper Captain Ryan |
 Joe SawyerWhitey, burly henchman | Whitey, burly henchman |
 Mack GraySmoke, thin henchman | Smoke, thin henchman |
 Eddy ChandlerTrooper Haynes, Car 45 | Trooper Haynes, Car 45 |
 Robert KentTrooper Blatzky | Trooper Blatzky |
 John HowardTrooper Carney | Trooper Carney |
 Alfred DelcambreTrooper Jamison | Trooper Jamison |
 Howard WilsonDutch | Dutch |
 Hector V. SarnoFrench Charley | French Charley |
 Eddie DunnMack | Mack |
 Jack CheathamRadio Sgt. Meyers | Radio Sgt. Meyers |
 Russell HoptonDispatch Operator Harper | Dispatch Operator Harper |