Will Kate Beckett run for the senate? That's the major cliffhanger in the series that has not answers right now, but spoilers for "Castle" season 8 teased tension between Ryan and Esposito.

Alexi Hawley told TVLine that when the show returns Kate would be the new captain as part of their effort to "shake things up" a bit.

"We want to simplify the cases a bit so we can spend more time getting into our characters. And it's across the board - it's Alexis, it's Ryan and Esposito, it's Martha, it's the new characters coming in, [played by] Toks [Olagundoye] and Sunkrish [Bala].... And then of course you have Castle and Beckett," he said.

"The important thing to say bout them is: 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. So we're going to have fun. It's going to be emotional at times, it will be romantic, it will be everything," the showrunner added.

Terence Paul Winter, meanwhile, teased more "Castle" season 8 spoilers when he hinted of tension between Ryan and Esposito.

"It's a very interesting story with the boys. After seeing Beckett ascend the ranks, Ryan and Esposito (Seamus Dever and Jon Huertas) are realizing maybe it's time for them to start looking upwards with their career," he said.

In their effort to rise up the ranks, "they start to butt heads a bit, so the two at times get a bit at odds - but in a fun way."

Watch out for more "Castle" season 8 spoilers which will be published here when they come along ahead of the airing date on Sept 28. The season premiere was announced to be a two-parter and the first part would be about Rick who might stumble into some answers to a past mystery when Kate goes missing.