Ellen Gray's weekend TV picks
* THE WALKING DEAD. 9 p.m. Sunday, AMC.
The zombie drama returns for its fourth season with Rick (Andrew Lincoln) and his band of survivors putting down roots, literal and metaphorical. Outside the prison walls, undead chaos still reigns. Don't even think about getting comfortable.
* LAST TANGO IN HALIFAX. 8 p.m. Sunday, WHYY12.
This episode, the season finale, is the one that convinced me "Last Tango" was more than a sweet story about old people in love. Anne Reid turns in an uncomfortable but prize-worthy performance as Celia, who, after learning that her daughter is gay - and guess who's coming to dinner! - behaves so badly that Alan (Derek Jacobi) realizes the gulf between them might be too wide to bridge.
* THE WHITE QUEEN. 9 p.m. Saturday, Starz.
The next-to-last installment of this miniseries about the queen (Rebecca Ferguson) who would become grandmother to Henry VIII arrives at one of the sadder episodes in British history, "The Princes in the Tower."
* SIGNED, SEALED, DELIVERED. 9 p.m. Saturday, Hallmark.
If TV hasn't seemed quite the same since "Touched by an Angel" was canceled, this might be for you. A Hallmark movie from "Touched" producer Martha Williamson, it's a whimsical story about postal workers whose job it is to deliver lost mail. It's been picked up for a 2014 series.