The upcoming season 11 finale of Fox's Bones will be a big one in many respects.

The Bones season 11 finale airs next week, and executive producer Jonathan Collier is promising high stakes ahead. The episode, titled "The Nightmare Within the Nightmare", will feature the return of The Puppeteer serial killer.

"We've pulled out all the stops," Collier told TVLine recently, of the finale. "We're really trying to challenge our characters, challenge our relationships, challenge even the safety of those we love and wrapping it up with an incredible surprise. [The Puppeteer Killer storyline] goes to a place you're never expecting but that makes complete sense."

The episode will feature the Jeffersonian investigating the Puppeteer killings once more, as Brennan (Emily Deschanel) deals with some of her own stuff. She will find herself feeling guilty about her retirement last year, and "blaming herself for not stopping the serial killer earlier," as the Fox synopsis states. "However, little does she know she might be in some trouble of her own."

Meanwhile, Bones fans are becoming increasingly sad as the series marches toward its final season. The 12-episode season will air in 2017 and luckily, the show's producers are hoping to provide a big sendoff for the long-running series.

"We want this to be a grand ride off into the sunset for the final 12 episodes for next season," said Bones executive producer Michael Peterson in a previous interview. "We will bring back as many guest cast as humanly possible and whoever is available. We'd love to get Cyndi [Lauper] back. We don't have Betty [White] for the second half of this season, but we'd love to have her come back. Next season, we have one episode in particular that we would love to have her back for. We are leaving it wide open."

The final season was originally supposed to begin during the fall 2016 season, but Fox decided to push it back to make room for the new show Pitch.

Bones airs Thursdays at 8 p.m. ET/PT on Fox.

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