Michael Kitchen, left, and Honeysuckle Weeks are shown from the series "Foyle's War," premiering its new season on "MASTERPIECE Mystery!" on PBS on Sept. 15, 22, and 29. AP Photo/PBS- ITV, Bernard Walsh Michael Kitchen, right, and Honeysuckle Weeks are shown from the series "Foyle's War," premiering its new season on "MASTERPIECE Mystery!" on PBS on Sept. LOS ANGELES (AP) - The premise: A small-town policeman goes big time with cloak-and-dagger intrigue, showing the spymasters how it should be done. The change of pace for retired Detective Chief Superintendent Christopher Foyle of Hastings, England, comes in Sunday's return of "Foyle's War," which moves the PBS "Masterpiece Mystery!" series from the stark horrors of World War II into the shadows of the Cold War. For Foyle addicts - and there are millions of them in the U.S. and worldwide - it's a chance to see their hero on a different stage. For those yet to discover the smartly written and produced series starring the remarkable Michael Kitchen, it's a good time to join in. Shifting Foyle to security agency MI5 in London (with Dublin playing stand-in), lets newcomers to the drama avoid the fog of confusion. There's also easy accessibility: The three new episodes can be streamed on digital channel Acorn TV the day after their PBS debut, and Acorn has the library of past seasons on home video and streaming. Longtime fans may miss cast members who weren't able to come along this season, including Anthony Howell as Detective Milner and Julian Ovenden as Foyle's war-hero son. But consolation comes with the return of Honeysuckle Weeks as Foyle's loyal sidekick, Samantha, married to a political hopeful (Daniel Weyman), and Ellie Haddington as the chillingly efficient MI5 bureaucrat Miss Pierce. Viewer devotion and an unusual production deal with Acorn made the program's seventh-season return possible. First, however, series creator Anthony Horowitz had to decide there could be life for Foyle after the cease-fire. "When I got to the end of the war, 1945, I thought that was the end of that," said Horowitz, a novelist as well as screenwriter. But urging from fans and executive producer Jill Green, who also happens to be Horowitz's wife, did the trick. It was a fantastic thing, in the end. It reanimated us, inspired us, gave us a new language, characters and new things to play with," Horowitz said. And I also was delighted to have left policemen and police stations and bodies in the libraries behind me. He uttered that last sentence lightly, but noted later that his 15 years working on the series comes to about three times the length of WWII. The task hasn't been easy: The show builds its well-plotted crimes on a bedrock of history and careful period set and costume design. It all showcases Kitchen's magic in portraying the steadfastly moral, humane Foyle. What the actor can convey with a coolly unblinking gaze or twitch of the lip requires scenery chewing from lesser mortals. He's "sheer class," said Weeks, herself a charmer as earnest Sam. He's so subtle, and somehow he manages to bring layer upon layer of experience and truth and subtext in the simplest of gestures. It's extraordinary. It was American cooperation that made this season possible. "Foyle's War" proved such a success for DVD distributor Acorn, part of RLJ Entertainment, that it bought the series and joined British broadcaster ITV in funding more of the drama. Horowitz is already at work writing additional episodes for next season, and he and Green dropped hints of what's to come. "We're taking a very, very close look at Foyle's private life and developing it in a very interesting and, I hope, enjoyable way," Horowitz said. Does that suggest love may be in store for Foyle? The longtime widower has done nothing more than exchange warm glances with a murder suspect, an attractive blonde, in season three's "They Fought in the Fields" by writer Rob Heyland, among the few episodes Horowitz didn't craft. "Those are two words I would only use if they are together: 'potential' and 'romance,'" Horowitz said, while Green said they're attempting a "gentle" affair for their leading man. Adds Horowitz, cheerfully: "If there's going to be romance in 'Foyle's War," I'm going to be the one who damn well writes it." Lynn Elber is a national television columnist for The Associated Press. She can be reached at lelber@ap.org and on Twitter@lynnelber.