The "Burning Man" of the mountain biking world, this race attracts some of America's most eccentric mix, as competitors pedal a 24-hour loop course through the wild and dangerous cacti forest of the Sonoran Desert. The squad experiences equipment breakdowns, a race-stopping emergency, night time exhaustion and the fight to work their way onto the podium.

Set north of the Arctic Circle, this three-day cross-country ski race is considered one of the most challenging of its kind due to unpredictable weather conditions. The harrowing first day is full of learning curves, a white-out on day two challenges all the and a looming storm on the final day turns the entire race upside down.

The athletes head to the Atacama Desert, the driest place on Earth for a 100-mile foot race that could be the mental and physical breaking point of the race season. With the sun beating down on their bodies, it will take the pure determination of their minds to reach the finish line.

The Adventure Xstream Moab race in Utah is a riveting one-day, 60+ mile adventure competition. The race marks the first time Simon, Turbo, Rory and Hunter compete as a four-person team. Pushing the squad physically and emotionally against one another, they battle a crippling six-mile canyon climb, steep rope descents and a costly navigation blunder in their quest to make the podium.

Deemed the hardest mountain bike race in the world, the MB Race Culture Velo set in the French Alps features 70km, 100km and grueling 140km course option with over 7,000 meters of single-track climbs, and harrowing descents. On and off the track, the athletes encounter a few obstacles along the way. Rory tries to overcome her mountain biking inexperience and retain her racing legacy. Simon's bike goes missing and is forced to maneuver the rugged terrain on a rental and Hunter's cramping threatens to take him out of the race entirely. On a high note, Turbo is pacing ...

This very demanding Quadrathlon race is amidst the scenic rolling hills of Aberfeldy, Scotland. The competition features a nearly one-mile swim across Loch Tay, 60 miles of fell running over seven hills above 3,000 feet, a seven mile kayak, and a 34-mile road bike. Simon and Turbo, as Team Canada, push and pull one another over some daunting moments through their combined sense of discipline, while the young and hungry Hunter and Rory, as Team America, push forward full force. It'll take more than just trash talking to beat the mental stamina required to reach the ...

The Boundless athletes take on the punishing Ultimate Mountain Challenge, the toughest event in the multi-day Vail Mountain Games festival. Cheered on by friends and family, they complete in standup paddling, mountain biking, trail running and a road bike time trial - each race pushing the athlete's fears, injuries and endurance in ways they never expected.

The Superbowl of Obstacle Course Racing (ORC,), the Spartan Beast World Championship, brings the world's top OCR athletes together for a 38-obstacle course track in Squaw Valley, California. Returning to the sport that put him on the map, Hunter is bringing Team Boundless to his wheelhouse for a change, pushing himself further and faster than ever before while preparing Simon, Rory and Turbo for a pounding and punishing experience.

The Bruce Peninsula Multisport Race is a 100km competition that features 16km kayak, 62km of treacherous road and trail biking and 21km of running along the beautiful Niagara Escarpment in Ontario, Canada. In teams of two, Simon and Rory are confident they will knock the wheels off Hunter and Turbo. But with Hunter's "American muscle" and Turbo's "Canadian hustle," they are sure they will give Simon and Rory a run for their money. As the miles add up, and the path winds in unexpected directions, Hunter and Turbo begin to turn on one another, allowing Simon and Rory to...