The final episode of "Bones" season 11 is coming in a week's time, and it is expected to be one of the most spine-chilling yet emotional episodes viewers will ever have seen thus far.

Titled "The Nightmare in the Nightmare," episode 22 will bring back one of the creepiest serial killers ever introduced in the series. It will also follow Brennan as she faces another danger.

Based on the official synopsis for the episode, the season finale will largely focus on the Jeffersonian team's quest in finding out the identity of "The Puppeteer."

"The team dives back into investigating a serial killer from the past, attempting to find "The Puppeteer," who lives with his victims' bodies before disposing them. Meanwhile, Brennan works through her guilt over her retirement last year, blaming herself for not stopping the serial killer earlier. However, little does she know she might be in some trouble of her own," says the synopsis. 

The season finale will see how the team solves the case which came up earlier this season, and which involves a dangerous serial killer. The case can be traced back to episode 13, when the team found out about this puppeteer who lives with the corpses of his victims before discarding them after several months.

Meanwhile, the guilt-ridden Brennan is oblivious about the danger awaiting her while she's busy blaming herself for not stopping the serial killer when she had the chance.

"Bones" season 11, episode 22 airs on July 21, 9:00 P.M. on FOX.