Written and filmed to reflect the reality of life in the Royal Navy and the Royal Marines in the 1970s, most stories focus on the Captain and his fellow officers, with subplots dealing with life on the lower decks. Episodes typically featured a variety of events at sea (the Cold War, smuggling, the evacuation of civilians from crisis-hit places, etc.), as well as the personal lives of officers and ratings and the impact their personal lives had on their professional lives and duties.
