Bones fans should get ready for a cliffhanger in the season 9 finale that in some way involves both Booth (David Boreanaz) and the mysterious Ghost Killer.

Season 10 to End Series with Brennan & Booth Haunted by Ghosts of Victims?

Bones executive producer Stephen Nathan recently spoke with TVLine about what they had planned for the series moving forward with season 9.

"We're ending the year in a very surprising way," Nathan revealed. "Two different stories converge and it throws Booth and Brennan's [Emily Deschanel] work relationship into turmoil and causes big, big changes for our people."

The Ghost Killer Revealed to Not be a Real Person?

One of these stories involves "a promotion that seems to exist within the FBI and they have their eye on Booth to fill this position," according to Nathan. Meanwhile, there will also be time devoted to the Ghost Killer, the mysterious serial killer lurking in the shadows who has not revealed their identity.

"The Ghost Killer [arc] becomes far more complex and conspiratorial, and very well might lead back to the FBI," Nathan said.

Luckily, fans do not have worry about Bones going off the air on an unresolved cliffhanger, as Fox has already renewed the procedural for season 10.

The TVLine report claims that the series is moving forward with an intriguing new plan for season 10 that, according to Nathan's previous comments, will "temporarily change the landscape of the show."

This could potentially mean that Booth is promoted to a higher status and possibly becomes Brennan's boss, which would certainly change the dynamic of Bones.

Bones season 9 returns on Monday, March 10 at 8 p.m. on Fox.

Watch the promo for the next episode of Bones below: