Showtime Sun., 10 p.m.
Dominic West, forever known as McNulty from The Wire, is a happily married public-school teacher, spending the summer on Long Island with his wife and kids. Ruth Wilson is a waitress in a local diner, a gal with a hard-luck past and a shaky marriage. She catches his eye and gets under his skin. What happens next isn't exactly a surprise – see the title – but the layered story is the smartest and saddest drama anywhere this fall. West is impressively deft as a husband who never realized how weak he is. Joshua Jackson and Maura Tierney are excellent as the cuckolded partners. The Affair tells the story from multiple points of view, exposing all the nooks of heartbreak under the summer-fling surface.