'Big Bang Theory' Finale Spoiler: Expect Big Cliffhanger, Says Wolowitz Actor

The highly anticipated season finale of CBS's hit comedy show, "The Big Bang Theory" will feature a major decision for one of the characters which could put a relationship in jeopardy.

"This time, the adventure is for Leonard … Howard finds Stephen Hawking's crew is sending out an expedition to the North Sea, and he gets Leonard a job, going on a boat for four months," Simon Helberg, who plays Howard Wolowitz, told AP.

Leonard, who is played by Johnny Galecki, will have to choose whether to go on the scientific expedition and leave his girlfriend Penny, played by Kaley Cuoco, behind for four months.

"The obstacle is Penny and Leonard have never been better," Helberg continued. "So, is he really going to leave her for four months?"

Helberg also revealed that Raj, played by Kunal Nayyar, will be part of an interesting development with his new squeeze Lucy, played by Kate Micucci.

The show has jumped to the top of the charts in six seasons and viewership has more than doubled in that time. This year's first episode was its most-watched first-run episode ever, with more than 20 million viewers.

But it is not just domestically that the show is a hit. Canada, the U.K and Brazil have recorded some of it largest viewerships.

"I think we're all having a good time," Helberg explained. "And I think the show is far from being stale. It is kind of constantly, not reinventing itself, but just expanding on these characters. So, yeah, I think we're going strong for now, as long as people keep inviting us in."

The season finale of "The Big Bang Theory" airs Thursday night on CBS.