The latest "Castle" season 8 spoilers indicate that the premiere episode will focus on Kate Beckett's (Stana Katic) disappearance and Rick Castle's (Nathan Fillion) struggle to find her.

Castle will reportedly receive a call from a stranger asking him to go on a dangerous mission to find his missing wife. It was said that he would have to do several tricky tasks to please the caller.

"A call from a mysterious stranger ignites an explosive chain of events; the story is first told from Castle's perspective as he searches for Beckett," synopsis read, via Yahoo! News.

"Rick, on the other hand, will have his own share of troubles as his smart daughter Alexis will join his PI Firm. But she is not the only new colleague for the mystery novelist as the father-daughter duo will be joined by a new security specialist, Hayley Vargas, played by series regular Toks Olagundoye."

The publication added that Castle and Beckett may not just get the happy ending fans wanted come season 8. It was said that their decision to go in different direction professionally may take a toll on their relationship.

Meanwhile, "Castle" season 8 spoilers also suggest that fans of Ryan (Seamus Dever) and Esposito (Jon Huertas) can look forward to "very exciting" premiere. Beckett's promotion will reportedly force the duo to examine their respective careers.

"After seeing Beckett ascend the ranks, they're realizing maybe it's time for them to start looking upwards in their own careers," showrunner Terence Paul Winter told TV Line.

"In doing so, they start to butt heads a bit, but in a fun way, because the dynamic between those two has always been 'two brothers.'"

The premiere episode of "Castle" season 8 airs Sept. 21 at 10 p.m. EST on ABC. Watch the trailer below:

Tune in for more "Castle" season 8 spoilers, news and cast updates.