Don Winslow (titular hero of the serial "Don Winslow of the Navy") is reassigned to the United States Coast Guard, to guard the coast against saboteurs and sneak attacks.
| Actor | Role |
|---|---|
 Don TerryComdr. Don Winslow | Comdr. Don Winslow |
 Walter SandeLieut. 'Red' Pennington | Lieut. 'Red' Pennington |
 Elyse KnoxMercedes Colby | Mercedes Colby |
 Philip AhnHirota | Hirota |
 June DuprezTasmia | Tasmia |
 Edgar DearingC.P.O. Ben Cobb | C.P.O. Ben Cobb |
 Lionel RoyceReichter | Reichter |
 Henry VictorHeilrich | Heilrich |
 Charles WagenheimMussanti | Mussanti |
 Nestor PaivaThe Scorpion | The Scorpion |