"Castle" Season 8 will not only feature new characters as Adam Baldwin, a former character in the show, will be returning. The character of Baldwin, Detective Ethan Slaughter, was first introduced in the fourth season of the show.

Detective Ethan Slaughter is this rough cop who Rick Castle had a ride along with in an episode called "Headhunters," Entertainment Weekly shared. It remains unknown why the show will be featuring Slaughter again as details about the plot is being kept under the wraps. The only detail that was revealed about Slaughter is that he will be seen early in the season.

It is rumored that Slaughter's arrival would have something to do with the new role of Kate Beckett. Beckett and Castle always investigated different cases together but because of Beckett's promotion, Castle might need someone to work with and it is said to be Slaughter. Another speculation about Baldwin's arrival in "Castle" Season 8 is that Beckett might need someone to be the new detective for New York City Police Department, TV Fanatic shared.

"Castle" Season 8 will be featuring Beckett being the Captain at NYPD and according to the showrunner, Alexi Hawley, her new position will be resulting to some trouble in paradise for her and Castle, Breathecast reported. He shared, "The important thing to say about [Rick and Kate] is that the show has always been and will always be about their love affair. But we're looking to add some drama to it, some spark to it. We're going to have fun. It's going to be emotional at times, it will be romantic.... It will be everything."

"Castle" will be back on Monday, September 21. The first episode is entitled "XY" and the new characters are reportedly to be introduced in the season premiere such as Toks Olagundoye as Hayley Shipton. Watch it only at ABC.