The cast and crew of "Castle" will have a lot to reveal about the future of Richard Castle (Nathan Fillion) and Kate Beckett (Stana Katic) in the premiere episode of season 8 titled "XY".

The sequel, which is scheduled to be aired on ABC at 10pm on Monday, 21 September, will mainly focus on the struggles of popular onscreen power couple as they try to adjust to their new lives.

The season will begin with the introduction of Katic's character as the new captain and the mystery novelist in the private investigation firm with daughter Alexis (Molly Quinn).

In a 30-second-long trailer, the detective can be seen celebrating her success with husband, and the new private investigator being impressed with his daughter's ability to close four cases. But it gradually takes viewers through a few action-packed scenes, which ends up showing Richard in danger.

The official synopsis of episode 1 reads: "After passing the Captain's exam in the Season 7 finale, Beckett was surprised with an offer to run for State Senate. In the action packed season premiere, Castle and Beckett are adjusting to Beckett's career change, when a call from a mysterious stranger sets off an explosive chain of events".

Meanwhile, creator Alexi Hawley teased that the detective's obsession to solve cases will have possible impacts on her relationship with Richard. "The beginning of this season is that that obsession, that part of her DNA, is still there, so she needs to deal with that in a way that impacts their relationship", TV Line quoted him as saying.

So "Castle" fans can expect some interesting sequences between Richard and Beckett in the premiere episode of season 8 titled "XY", which will be aired on ABC at 10pm on Monday, 21 September.