Bert (guest star Brian Posehn) reunites with the gang in the upcoming episode of "The Big Bang Theory" season 10.

Titled "The Separation Agitation," this week's episode will see the return of the socially awkward Caltech employee. According to the official synopsis, Bert comes back to the picture and introduces the gang to Rebecca (guest star April Bowlby), the new woman in his life. Meanwhile, Bernadette (Melissa Rauch) comes back to work after her maternity leave. She and Howard (Simon Helberg) must deal with separation anxiety, as they leave Halley in a day care for the first time.

Bert's latest appearance this season was in episode 16, in which he became involved in Sheldon (Jim Parsons) and Amy's (Mayim Bialik) first fight. The couple had an argument about their privacy while they were having a random dinner with him.

CBS has recently released a new teaser for the episode. It kicks off with Raj (Kunal Nayyar) asking his friends to help find him a new girlfriend. Leonard (Johnny Galecki) asks Penny (Kaley Cuoco) if she has any friends Raj could date. "I already set up Howard and Bernadette, it's your turn to ruin some poor girl's life," Penny tells her husband. The next scene cuts to Raj wondering what Amy had that made her attractive to Sheldon. The genius physicist says he likes her "mind and body," surprising everyone in the room with his answer. Amy then explains that Sheldon is actually pertaining to her blood type. "Relax, we have the same blood type. He knew he could harvest an organ," she nonchalantly responds.

Only two more episodes are left until the end of season 10. Ahead of the show's finale next month, CBS has recently announced the sitcom's renewal for seasons 11 and 12. All original cast members (Cuoco, Parsons, Galecki, Nayyar, and Helberg) are confirmed to reprise their respective roles, while Bialik and Rauch are still in the process of negotiating new deals with the studio.

The 10th season of "The Big Bang Theory" airs every Thursday at 8 p.m. EDT on CBS.