Ben Stiller Probes Bear Grylls’ Dark, Damp Cave in ‘Running Wild’ Teaser (Video)

The actor visits Scotland in NBC's new Hollywood-meets-wilderness show

Ben Stiller guest stars in the next episode “Running Wild With Bear Grylls,” which NBC is teasing with a video of the “Night at the Museum: Secret of the Tomb” actor venturing into a real life tomb of sorts — a cavern embedded deep within the Scottish wilderness.

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“It goes a long way in,” says TV host and famed British outdoorsman Bear Grylls.”I'm hopeful we're going to find somewhere where we can shelter for the night.”

Stiller shines his flashlight into the dark and creepy natural crevice.  ”This is amazing,” he says “I cant get over this.”

“That's the mineral build-up,” Grylls explains. “If you lean back you lose your grip. Just have confidence, lean forward. Trust the grip. Stay on the white stuff.”

Stiller looks uneasy. Moments later he loses his footing on the cave floor, which was slippery from condensation.

It's the second week in a row Bear Grylls has run wild with one of Hollywood's top actors. As TheWrap previously reported, the show's July 27th premiere featured Zac Efron taking off his shirt and opening up to Grylls about his problems with addiction.

See video: Zac Efron Discusses Addiction to ‘Social Lubricant’ With Bear Grylls

“‘Running Wild’ is where I get to take some of our most loved Hollywood stars out on a great 48-hour adventure,” Grylls says in another video describing both the premise and purpose of his new unscripted NBC show. ”And I think what has been powerful for me is seeing how the wild can transform people, and it can empower people, and it can reconnect them with who they are. I think the danger of fame is that it's easy for people to go a little bit mad.”

Stiller's “Running Wild With Bear Grylls” episode airs Monday, Aug. 4 at 8 p.m. ET.