Jack's family join his this series in his quest to experience the planet's most extreme thrills. This week they drive across vertical rock faces.

Jack and his parents travel to Argentina, where they go on a two-day dog-sledding expedition into the mountains in cold weather.

Joanna Page, Jesse Metcalfe and Reggie Yates travel to New Zealand with Jack, where they bungee jump from Auckland Harbour bridge. They then make the trip to Queenstown where they have to face the world's largest canyon swing. They then have to dangle off the side of a mountain attached to a helicopter.

Joanna Page, Jesse Metcalfe and Reggie Yates continue their adventure with Jack in New Zealand. The experience a night-time bungee jump high above Queenstown before moving on to Dubai. Once there they play a game of camel polo and compete in a powerboat race.

Jack travels to the Canadian Rockies with Natalie Imbruglia, Billy Boyd and Konnie Huq for a series of different challenges. Firstly they have to climb Mount Fable but they soon find themselves in difficulties. They also go mountain biking in some woods and experience underground caving.

Natalie Imbruglia, Billy Boyd and Konnie Huq travel to Hawaii with Jack. Whilst there they try out free diving and they then go on a kayaking trip along the remote volcanic coastline. A the end of their trip they try out surfing.