The series stars Wendell Corey as Captain Ralph Baxter, head of the Harbor Command of a large coastal city. Baxter and the officers in his unit fought "dope smugglers, murderers, and other assorted villains". Baxter differed from other police officers in that he had studied criminal psychology, enabling him "to figure out what the criminal mind would do under certain circumstances." Although series had a water setting, much of Baxter's activity occurred on land as he used his police car to track down suspects.