Ep 20. That '70's Show

In the Castle (2009) season 6 episode 20 titled "That '70s Show," Castle and Beckett team up to solve a murder case that takes them back in time to the 1970s. The episode begins with Castle attending a murder mystery costume party where he is dressed as a 1970s cop. During the party, a woman named Mandy Sutton is found dead, and Castle immediately jumps into action to try and solve the case.

As Castle and Beckett begin their investigation, they discover that Mandy was a devoted employee at a company that produced pinball machines in the 1970s. They also learn that Mandy was planning a retro-themed party for her coworkers, which leads the detectives to believe that the murder may have been related to the upcoming event.

The investigation takes Castle and Beckett on a wild ride through the 1970s as they meet a cast of colorful characters including Mandy's former boss and several of her coworkers. They also encounter a group of roller skaters who were involved in the pinball industry at the time.

As they dig deeper, Castle and Beckett uncover a web of lies and deceit that ultimately leads them to the killer. Along the way, they encounter several challenges including a car chase and a shoot-out. However, they are able to overcome these obstacles with their wit, determination, and trust in each other.

Throughout the episode, the 1970s theme is evident in the costumes, music, and overall vibe of the show. The use of flashbacks and vintage footage also adds to the authenticity of the time period. Castle's love for all things retro and his admiration for classic detective shows also come through in this episode.

Overall, "That '70s Show" is a fun-filled episode that will have viewers laughing, guessing, and ultimately cheering for Castle and Beckett to solve the case. The use of the 1970s theme adds a unique twist to the show, and the chemistry between the two main characters is as strong as ever. Fans of the show will not want to miss this episode.