"The Big Bang Theory" is back for its ninth season and is already in full swing. The show was the ratings winner last Monday night with a 3.8 demo rating (18-49) and a total of 15.23 million viewers tuning in for its second episode, as reported by Zap2It's TV by the Numbers. 

The popular CBS comedy returns next Monday, Oct. 5, with its third episode titled "The Bachelor Party Corrosion." The upcoming episode will no doubt be another smashing success for the network as fans of the show tune in to see what their favorite gang will be up to next. 

In the all-new episode, the guys head to Mexico. Howard and Raj arrive to "kidnap" Leonard to throw him a belated bachelor party weekend. While Leonard is excited and raring to go, Sheldon, being his usual self, insults and second-guesses their plans. In the end, it is Sheldon who ends up being tied up and "kidnapped" for the trip. Unfortunately, the roadtrip gets bumpy when the guys get a flat tire and their skills are tested. 

Meanwhile, the ladies have their own girls' night as Bernadette and Amy throw Penny a mini-bachelorette party. Amy contemplates getting a makeover, which includes getting her ears pierced in order to cope with her break-up. Bernadette and Amy guilt-trip and nag Penny about the fact that she has yet to tell her family that she has eloped with Leonard. As Penny gathers up her courage to call her family, Amy reveals that she hasn't told her family about her break-up either. 

Keith Carradine is set to return as Penny's father, Wyatt. Carradine's last appearance on the show was back in season 4's ninth episode titled "The Boyfriend Complexity." 

Fans can also check out official images from and the trailer for the upcoming episode. 

"The Big Bang Theory" season 9 airs every Monday at 8 p.m. ET on the CBS Television Network.