Louise Lombard Louise Lombard

Perhaps inspired by the Las Vegas setting, the creators of CBS' CSI must never sleep. Rather than resting on their laurels, the makers of the original forensic phenomenon continue to surprise with fresh approaches to the show's storytelling. One of the ways the CSI formula has resisted becoming, well, formulaic is the addition of new faces to the mix. The brash and uncompromising Sophia Curtis, played by Louise Lombard, is one of these emerging characters.

In tonight's episode of CSI (Thursday at 9 pm/ET) — the first of two parts entitled "A Bullet Runs Through It" — Curtis finds herself in a very precarious situation. Normally an investigator, she suddenly becomes the one being investigated after a shootout leaves a cop killed by what is suspected to be friendly fire. It's the first time Curtis, who has grown into a featured character, will take center stage.

"She killed one person and there's a possibility she killed somebody else," Lombard explains to TVGuide.com during a break in filming the episodes. "It's a tragic start to the two parts. It's a big horrible mistake, something no cop wants to be involved in. They're being shot at and they have to return fire."

The incident starts fast and furious with a routine traffic stop turning into a pulse-raising chase and gun battle. The resulting carnage leaves one officer down and a stretch of ballistics evidence that the CSI team must piece together to assess the exact damage inflicted by one of their own.

Lombard relishes the chance to bring an embattled Curtis to the forefront. Having originally signed on to play a large role in the CSI ensemble, the Brit actress' contributions had to be reduced last season after she learned that she was pregnant. With her baby since born, Lombard is now getting a chance to fully develop her character.

"[Sophia] is very single-minded about what she wants to do and why she wants to do it," declares Lombard. "That can make her a little abrasive and undiplomatic. But basically, she wants to be a cop. That's partly because her mother was one and partly because she wants to get the bad guys."

Lombard's interest in the role grows out of how she views Sophia in contrast to the show's other characters.

"There's really not much gray area with her, as opposed to most of the CSIs," she admits. "They are all scientists, so it isn't necessarily about good and bad — it's about viewing the evidence and withholding a judgment. There's much more restraint. But that's not really how Sophia approaches her job. It's nice to play her, because she's in conflict with the rest of the CSIs."

That conflict is sure to be at the heart of both segments of "A Bullet Runs Through It," though each episode has a different director — yet another intriguing decision by CSI producers. Both narratively (the show's once-standard use of dual story lines has been employed less and less frequently) and stylistically (maverick filmmaker Quentin Tarantino was brought in to direct last season's finale), CSI continues to take chances. Lombard credits that sort of freethinking with the show's success.

"I think the team behind CSI are an incredibly talented bunch," insists Lombard. "When it's right to stick to what audiences know, they do that. And other times they break from that. The idea came up for 'A Bullet Runs Through It' and to do it justice, they decided it would need two episodes. They do what they need to do to tell the best possible story. That, I think, is why it's the most popular show on television."