After seven years of marriage, Alan and Celia discover that wedded bliss isn’t always blissful. Clashing politics, Alan’s new job and a wild local lad create tension. Caroline gets emotionally embroiled at work. Alan’s brother visits. See what else unfolds in season four of “Last Tango in Hailfax.” The new season airs on Sundays at 7 p.m. starting September 20.
Catch up on the new season here or via the PBS app.