In the seventh season of “Foyle’s War,” Detective Chief Superintendent Christopher Foyle (Michael Kitchen), now retired, has just returned from the United States to an England clad in the drab, hungry and dismal gray of the post-World War II years. There are food shortages, lack of jobs and restless soldiers who are tired of being in uniform; they want to come home.

This season is set at the start of the Cold War, a term created by a notable British author, George Orwell, who wrote “1984.”

Looking only to return to the comfort of his home in Hastings, Foyle is greeted on his arrival by MI5, the counterintelligence Security Service, and asked to investigate a suspected Soviet spy ring. His disinclination to get involved is overcome by two factors: His American trip caused an embarrassing diplomatic fuss for the British government, and more importantly, the espionage investigation involves his former wartime driver, the newlywed Samantha Wainwright (Honeysuckle Weeks.)

In 1946, it comes down to whom you can trust in a world awash in refugees, hunger, rebuilding, corruption and a strong invasive enemy — the Soviet spy system, the KGB. Is that refugee real or an agent of the KGB? Who does that Englishman really report too?

“Foyle’s War” is a meticulously researched series that recreates the period down to food shortages, political restlessness, and the omnipresent cigarette smoke that chokes almost every scene. The new trio of episodes will start Sept. 15 on PBS.

RLJ Entertainment acquired the rights to “Foyle’s War” in November 2010 and created the three new episodes. Their brand, Acorn, focuses on British television shows including “Prime Suspect,” “Murdoch Mysteries” and “Midsomer Murders.” It will be streaming the “Foyle’s War” episodes on acorn.tv a day after PBS broadcasts them this month.

Subsequent episodes involve local politics, secret interrogations and the war crimes of World War II.

Against the murky shadows cast by espionage, Foyle’s uncompromising honesty is his greatest strength, if sometimes a trial to his friends. He isn’t afraid of treading on anyone’s toes even when threatened with return to the U.S. to face the consequences of his visit there.

The top officers at MI5 might end up regretting they asked Foyle to join them. As one character says disdainfully, “He’s not one of us.”

That’s lucky for them.

PBS trailer for Foyle's War, Season 7