Last night, Bones aired its 100th episode. That's a big deal, and congratulations are in order for the entire cast and crew.

But enough about the past. Let's focus on the future of this great, long-running show. Specifically: what will go down on the fifth season finale?

Star David Boreanaz has already said a "big shift" will take place on the episode, but E! News asked for more information from various key players this week. Series creator Hart Hansen described the finale as "a big deal and a big payoff."

As for Emily Deschanel?

"There are big changes, and decisions are made that affect the future for Booth and Brennan, but also the future for other characters as well," the actress said. "It puts next season in the air, and a lot of things could be very different from what we know on Bones."

Meanwhile, E! also asked the cast members to describe what's ahead in a single word. Their responses?

• Deschanel: Change
• Carla Gallo: Upheaval
• John Francis Daley: Unresolved
• T.J. Thyne: Tantalizing

Bones airs its season finale on May 20.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.