Famed adventurer and survivalist Bear Grylls raises his star power in his new series, taking celebrities -- including Channing Tatum, Ben Stiller and Zac Efron -- on one-on-one, 48-hour journeys into some of the wildest, most-remote locations in the United States and around the world. From skydiving into the Catskill Mountains, to battling the weather in Scotland, each episode chronicles a celebrity's experience of pushing body and mind to the limit to successfully complete the adventure.