Best friends Matt Galland, Danny Bryson and Blake Josephson are adventure enthusiasts who take on the unthinkable challenge: to run 100 miles in just four days through Utah's rugged backcountry wilderness. The guys think of the Wasatch Mountains as their own backyard and are all too aware of the dangers this harsh environment has to offer. They must scale jagged cliffs, dodge tumbling boulders and find a way back down from the snowy summits they ascend…all while they try to avoid bears and mountain lions. The trio’s physical and mental endurance is put to the test. Can these three best friends really overcome these obstacles and run four grueling marathons in just as many days?

Matt, Danny and Blake head deep into the Arizona desert, where they battle harsh winds, freezing temperatures, endless sand and deadly Slot Canyons. This course is designed to take the guys out of their element and push them to their physical and mental limits. Hypothermia becomes a real and imminent danger and forces the guys to decide whether to abandon their adventure or push through and complete the 130-mile journey.

Matt, Blake and Danny head to remote southeastern Oregon to confront a 10,000-foot-tall beast: the imposing Steens Mountain, which reigns above some of the wildest, most remote land remaining in Oregon. A massive winter storm is rolling in, foreshadowing the brutal four-day trek ahead. The trio’s endurance and mental resolve is about to be tested as snow, ice, wind and dangerous avalanche conditions threaten each and every step taken. The Steens Mountain not only tests Matt, Danny and Blake’s mettle but it also tests their friendship as they hike blindly through white-out conditions, scale razor-sharp cliffs and fight the elements to make their way back down the mountain toward the finish line.

Matt, Danny and Blake embark on a treacherous, three-day, 75-mile journey through Idaho’s infamous River of No Return Wilderness, an area of steep, rugged mountains; wild whitewater rivers; and deep canyons considered to be inescapable. Starting at nearly 10,000 feet high, the trio descends into a powerful river that was once battled and explored by Lewis and Clark. There, the guys must tackle dehydration, brutal rapids and unpredictable weather. When Danny suffers from lack of water, Matt and Blake must devise a new plan, in which all three can cross through this region’s beautiful yet deadly wilderness.

In Chiapas, Mexico, Matt, Danny and Blake venture into rather unknown territory – Cañón Rio La Venta. Starting their four-day adventure with a rappel into a 500-foot-deep sink hole, the three friends then bush-whack their ways through miles of jungle before reaching a vast canyon that for the most part remains hidden to the world. The team travels along this canyon’s treacherous river in an effort to reach a landmark known as the El Arco del Tiempo (Arc of Time), one of the world’s largest natural stone arches. But standing in their way are fierce rapids, jagged rocks and killer bees, which all test their physical and mental agility.

Matt, Danny and Blake head to Central America to take on the untamed jungles of Belize. This four-day, 75-mile journey takes them from one of the country’s highest points, the shrouded Victoria Peak, to their finish line at the Caribbean Sea. Few humans ever have walked this terrain, and nobody has attempted to run it – with good reason. Along the way, the guys face brutal terrain, torrential downpours, oppressive heat and humidity. And, to make things worse, they encounter deadly snakes, spiders and crocodiles. The merciless conditions finally may prove too much for these best friends.

The trio head to Torres del Paine National Park in Patagonia, Chile, a place referred to as "the edge of the world" for a gruelling 70 mile trip.

The guys venture into Costa Rica for an arduous, 4 day, 70 mile jungle adventure, consisting of rappelling down waterfalls and battling whitewater rapids.