The latest “Castle” season 8 spoilers revealed that the coming episodes will focus on Castle and Beckett’s relationship. It has long been rumored that the two will face several challenges that will force them to go their separate ways . Series executive producers claim that fans can expect the forthcoming episodes to feature several shake ups in their favorite couple’s lives.

According to "Castle" season 8 spoilers from IB Times, Nathan Fillion (Castle) said that fans should not be worried about what will happen to Castle and Beckett. He added that showrunners Terence Paul Winter and Alexi Hawley only wanted what was best for the couple.

"It's going to be great," Fillion said.

"In order for a show to continue and to move forward, things have to change. And things have changed, every year, for these two."

The actor added that he was not worried about the possible developments since he knew that the producers and writers are consistently thinking of ways to improve the show.

Winter and Hawley will take the reins from veteran David Amann. This will also the first time that "Castle" will air without guidance from series creator Andrew Marlowe and his writer-producer wife, Terri Miller.

Meanwhile, The Hollywood Reporter recently confirmed that "Neighbors" star Toks Olagundoye was cast as a series regular following Penny Johnson Jerald's exit from the ABC series.

"Olagundoye will play Hayley, a quick-witted, free-spirited former Scotland Yard police officer who works as a security specialist and isn't afraid to cross lines to get things done," the report said.

Jerald recently took to Twitter to announce to her fans that she will not be returning to season 8.

"To my 'Castle' fans around the world, as of late yesterday I am surprised and saddened to learn that I will no longer be a part of the 'Castle' family," she tweeted.

"Thank you all for your support and love. Hugs from PJJ."

"Castle" season 8 premieres on Sept. 21. Tune in for more spoilers, news and cast updates.