LIE TO ME: Lightman (Tim Roth, R) and Foster (Kelli Williams, L) in the season finale episode of LIE TO ME airing tonigh (9:00-10:00 PM ET/PT) on FOX. Fox Broadcasting Co. CR: Patrick Wymore/FOX

It’s the season three finale of Lie to Me tonight (9:00 p.m. ET/PT, FOX) and the story is a great way to call it a night for Kelli Williams.

Williams stars as Dr. Gillian Foster to Tim Roth’s Dr. Cal Lightman on the drama - and though her character usually has it all together - the season ender will unravel Foster’s strong exterior a tad.

“A client of mine - and an old friend - comes to ask for my help,” Williams begins. “She is one of three students who have started a social network kind of app. Something happens and she gets into a bit of trouble. I’m emotionally invested because she’s a dear friend of mine and I’m doubly invested trying to figure out what happened.”

It was a boon episode for the actress because she gets to demonstrate a level of anger that Foster rarely shows.

“I got to get really p—ed off. I get to do everything in this episode it seems,” she says elated. “I’m really upset, I’m really p—ed off, it’s very intense. And it’s a bittersweet one to film because we knew we were going to go on break and we haven’t gotten our renewal yet. I think it was a bit loaded with other emotions like is this our last time and the crew wondering if they’ve got to get themselves other jobs. So, there was a lot going on for us.”

The cast and crew won’t know if they’re getting another season for another couple of months. Still, both season two and three have seen a rise in viewers since the show changed its direction to include more action. But, until they all receive word giving the drama another go ’round, it’ll be a waiting game.

“It’s a strange wait,” Williams acknowledges. “We’ve had the same crew from the beginning and it’s a great group. I know everybody says that very liberally, but I mean it this time. If you looked at my face you would see no expressions of something else. We really get along and it’s really tight. You hope to keep everyone, but everyone’s got to go where the work is.”

Many hope the work stays put for a season four.