Merlin

Merlin
10/9c Syfy
The two-parter about the troll Catrina masquerading as a human in order to woo King Uther into marriage picks up post-wedding, with her influence over Uther becoming stronger by the day. Merlin, who knows well her true nature, plots to expose her, but the task is made all the more difficult when she accuses him of theft, a crime punishable by death. — Jeff Gemmill

Friday Night Lights

8/7c NBC
After his shocking ouster as head coach of the Panthers in last season's finale, Eric Taylor has a lot to prove in his new position with the East Dillon Lions. In the Season 4 premiere, Eric gets a taste of what's in store for his new squad...and it's not pretty. Tami, meanwhile, has her own set of problems to deal with after the controversial redistricting, and Matt and Riggins try to adapt to life after high school. — Brie Hearn

Smallville
8/7c CW
Annette O'Toole reprises the role of Martha Kent when she returns to Smallville with her boyfriend, Perry White (Michael McKean). Her visit is a surprise to Clark, who is preoccupied with searching for the Book of Rao, a key tool to defeat Zod. However, Martha's timing isn't all bad since Lois and Perry, as it turns out, have similar goals. They team up to work on a story about the Red Queen, but tracking her down isn't so easy. — Rhoda Charles

Real Time with Bill Maher
10/9c HBO
Conservative David Frum and liberal Bill Maher probably don't have much in common, but there's one thing on which they can agree: criticizing right-wing extremists. Frum's "Waterloo" comments after Congress passed a health-care reform bill preceded his (coincidental?) dismissal from the American Enterprise Institute, and Maher is bound to bring it up with tonight's panel, which also includes former Fox Business anchor Alexis Glick and author Salman Rushdie. Comedian Sarah Silverman is an interview guest. — Joe Friedrich

Primetime: What Would You Do?
9/8c ABC
What — if anything — would you do if you saw a woman in a bar who's too drunk to get herself home? Or if you saw clerks at an upscale boutique assuming that a group of  black teenagers is up to no good? And would you call the police if you saw somebody stealing a bicycle? Those are three of the scenarios played out by actors in real-life settings before real-life bystanders as ABC News' hidden-camera character test returns for its third season. John Quinones is also back as host. — Paul Droesch

Need to Know
8:30/7:30c PBS
The weekly public affairs show that's taking the slots previously occupied by Now on PBS and Bill Moyers' Journal premieres. A cross-media program hosted by Newsweek's Jon Meacham and one-time MTV correspondent Alison Stewart, it plans to highlight the week's best online news reports. The opener is slated to include stories on the Gulf of Mexico oil spill, the "open-carry" gun movement and the birth-control pill's 50th anniversary, as well as interviews with Bill Clinton and NYC mayor Michael Bloomberg. — Jeff Gemmill

NASCAR Racing
7:30/6:30c ESPN2
Far from the modern, cookie-cutter tracks that have infiltrated the NASCAR schedule sits Darlington Raceway in South Carolina. The 61-year-old egg-shaped oval hosts its only weekend of action beginning with tonight's Nationwide Series event, featuring Greenville native Jason Keller in his record 499th series start. Having split the last four races, Brad Keselowski and Kyle Busch are the hottest drivers on the Nationwide circuit, which has been more than a little attention-starved since Danica Patrick's last race in February. (She returns June 26.) — Roger Leister