The upcoming season 11 finale of Fox's Bones will have a cliffhanger, according to one of the show's executive producers.

The Bones season 11 finale is just a day away, and executive producer Jonathan Collier is giving a fun tease for what fans should expect.

"It will be a cliffhanger," Collier said in a new Entertainment Weekly interview. "A key character is threatened." He added, "We're promising everyone an incredibly surprising twist that will really reward our long-term fans."

The finale, titled "The Nightmare Within the Nightmare", features the return of the Puppeteer serial killer. Additionally, the finale will include some personal stuff with Brennan (Emily Deschanel) as she feels guilt about retiring last year when she could have stopped the Puppeteer. However, the Fox synopsis teases that she could be in danger. It remains to be seen if this involves the Puppeteer in some way.

The finale will be a scary episode of Bones, with showrunner Michael Peterson comparing it to the Alfred Hitchcock film Spellbound, mixed with Psycho.

"That's what we wanted to give the feel for: We really wanted to spook, and we also wanted to go to a villain who kind of sees the world like Brennan does," Peterson said in a previous Entertainment Weekly interview. "This is somebody who looks at skeletons and can see them as real people, and that's Brennan, but she is the good side of this. But there is a very dark side to what she does."

The upcoming final episode of season 11 will be the last one until the final season. The 12th and final season of Bones will only feature 12 episodes as opposed to the usual 22-24. It is expected to air in early 2017, a change from Fox's original plan of airing it this fall. The network is putting the new baseball drama Pitch in its place.

The Bones season 11 finale airs Thursday at 8 p.m. ET/PT on Fox.