Jack's global adventure kicks off in New Zealand, and he wastes no time in getting his young recruits stuck into their first challenge - walking a slack line, or tightrope, suspended over a sickening drop high in the mountains. To even get to its location, after being dropped off by helicopter, the recruits face a gruelling uphill mountain slog. Two things soon become clear to Jack - he has an unfit bunch on his hands, and he's going to face a lot of moaning over the coming weeks.

• Billy Boyd
• Elijah Wood
• Jesse Metcalfe