A new trailer for "Castle" season 8 has been released, and it warns that "everything you think you know is about to change." Without a doubt, things won't be the way they were in the previous season. Beckett has a new job and Castle has a new, intimidating partner. 

The preview shows even more and evokes a sense of thrill and danger. It starts off with the couple's celebration of Beckett's promotion to captain, which she admits makes her "exhilarated and frightened and everything in between." She will take over Victoria Gates' job in the precinct. 

The trailer then gives an idea how much of Castle's life at work will change in season 8. For the first time, fans get a glimpse of new series regular Toks Olagundoyes, set to play the role of Hayley Shipton, who overawes Castle with how quick and good she is at solving cases. It looks like she is good at giving someone a beatdown, too. 

The season 8 preview quickly shifts to a much more brooding aura with scenes such as Castle picking a bloody label that says, "Always"; someone who appears to be Shipton dodging gunfire; someone getting punched in the face; Beckett telling Castle she loves him as though for the last time; and him not understanding any of it. 

In the last seconds of the promo, which only lasts half a minute, Castle can be seen tied to a chair with a large tarantula crawling on his face as a man and a woman force him to spill Beckett's whereabouts in exchange for his survival. 

The promo shows that "Castle" season 8 will be a gripping season with new threats and new stories as well as newcomers joining the party. It will premiere on Sept. 21.