It's time for the Time Team's final mission.

NBC will air its first Timeless series finale promo Friday during a new episode of Midnight, Texas, and Clockblockers, you're in for a wild ride!

In the 30-second teaser, Lucy (Abigail Spencer) and Wyatt (Matt Lanter) vow to save Rufus (Malcolm Barrett) through any means necessary, with the help of Jiya (Claudia Doumit) and Flynn (Goran Visnjic). But their promise may come with caveats. 

"We are going to save history to save our future," Lucy says, as flashes of the Time Team in various states of distress appear. 

"I'm gonna to make things right," Wyatt declares, looking noticeably forlorn. 

But the kicker comes near the end of the teaser, when Rufus -- rocking an entire cowboy get-up -- comes barging into a saloon. "Merry Christmas, ya filthy animals!" he says with a smile. Watch the jam-packed series finale promo below.

While we count down to Dec. 20, the Timeless cast has been busy doling out tease after tease about the final two hours -- most notably about the very final scene of the show

"What I think is pretty cool is the end end -- the very end -- doesn't end on us. It doesn't end on the team. It's larger than us three, or it's larger than the team, which I think is cool," Lanter revealed to ET. "It's a little bit of a closed chapter for our characters, but things are left open at the end of this series finale. And our characters are still around, so you never know. There's always potential to have to save the world again."

Spencer reaffirmed Lanter's tease, specifically noting that Lucy, Wyatt nor Rufus close out the series. "I think that's a very big tease, that none of us are in the last scene of the entire [series finale]," she said.

Visnjic also shared that the Timeless swan song is a gift for the fans -- literally (the final episodes revolve around historical events set on Christmas Eve and Christmas Day) and figuratively.

"You would never see episodes like this on television; this is really made for fans," Visnjic told ET. "We're going to close all the loops. We're going to tie all the loose ends. We're going to come back with a storm of words that our fans love and memories from previous episodes."

Timeless airs its series finale Thursday, Dec. 20 at 8 p.m. ET/PT on NBC.

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