Holly Willoughby and Lee Mack present as eight celebrities undertake a series of sub-zero challenges designed to test them to their limits, both physically and mentally. They are being trained by extreme athlete Wim Hof, the man who once ran a half-marathon barefoot above the Arctic Circle, and climbed Mount Kilimanjaro in just his shorts and shoes. Those taking part are West End star Alfie Boe, singer and footballer Chelcee Grimes, Strictly professional Dianne Buswell, sports presenter Gabby Logan, weatherman and drummer Owain Wyn Evans, French footballer-turned-coach Patrice Evra, rapper Professor Green and actress Tamzin Outhwaite.
This week, the celebrities learn Wim's famous breathing technique, which proves to be an emotional experience for the group.
The celebrities are introduced to a surprise visitor that's close to Wim's heart, and they face a powerful man-made blizzard in nothing but their swimwear.
The celebrities are made to sweat in Wim's gym, where they learn how Wim's teachings have helped some of the world's most successful athletes. They also take on their coldest experience to date, the Ice Ladder - a spine-chilling endurance challenge that sees them battling to maintain their core body temperatures.
The celebrities must hold their nerve as they attempt to complete yoga stances on a tiny beam, which is suspended hundreds of feet above a frozen waterfall. They then attempt their scariest challenge so far - swimming underneath a frozen lake.
In the final episode of the series, the celebrities try to freeze their fear and complete the ultimate challenge of jumping from a 500ft high bridge.
