Last Tango In Halifax | PBS, Sunday, 8 ET/PT (times may vary)
Wedding plans are front and center in the finale of this British charmer, which stars Derek Jacobi and Anne Reid as long-separated lovers reunited late in life. The path to true love, however, does not run smoothly as a sudden burst of bigotry threatens to derail the marriage. But those in need of a wedding fix need not fear: Those bells are almost certain to ring for Rigsby and Van Pelt on The Mentalist (CBS, Sunday, 10 ET/PT), though fans may not see that as a completely happy occasion, as the plot is paving the way for the two actors' exit.
The Walking Dead | AMC, Sunday, 9 ET/PT
Cable's scariest and most popular series returns for an eight-week run, paired once again with its talk-show debriefing, Talking Dead (10 ET/PT). (That sigh of relief you just heard is coming from AMC, which is still recovering from a Low Winter Sun finale that didn't so much set as sink.) One warning for anyone new to Dead: This is a well-done series, but it's not for the very young -- or for those of any age with weak hearts or stomachs.
Masters of Sex | Showtime, Sunday, 10 ET/PT
Anyone who thinks you need crime, disease or zombies to power a series should check into this novel, serialized biography of sex researchers Virginia Johnson and William Masters, which airs its best episode yet this week. While reveling in the excellent performances from Lizzy Caplan, Michael Sheen, Beau Bridges and Annaleigh Ashford, notice the ease with which their unexpectedly gripping series switches from ribald humor to heartbreaking betrayal. Again, not a show for the very young -- but the title probably gave that away.