In the first episode, the teams set off from Mexico City – a gargantuan metropolis and the largest Spanish speaking city in the world.

Setting off from Panama City, they take to the Caribbean Sea, bypassing the most dangerous place in the Western Hemisphere - the Darien Gap.

As the 25,000km race to Ushuaia approaches the half-way mark, the four teams compete not just with each other but with the extreme altitudes of Peru.

To reach the next checkpoint - Cafayate in Argentina - teams must choose to travel through either Bolivia or Chile, but an unstable political climate in both countries puts everyone’s journeys at risk.

With three teams at the checkpoint at Cafayate in Argentina, one team is yet to arrive. Dom and Lizzie are over 24 hours behind their competitors and after a disastrous last leg must rely on all their ingenuity to claw their way back into the race.

With two teams at the checkpoint – Ilha Grande in Brazil – the remaining teams are engaged in a frantic race to avoid finishing the leg in last place.

The teams embark on the final leg of their journey, heading off on the 4,800 kilometre trek to the finish line in Ushuaia, Argentina, the most southerly city in the world. However, as they prepare to leave the last checkpoint, one of the teams reveals that they have run out of money and will not be completing the challenge. The three remaining pairs rely on different tactics to get ahead, benefiting from risky gambles, lucky opportunities and the kindness of strangers.

The five teams reunite for the first time to reveal fascinating insights into their different strategies and individual experiences - from their highest highs to their lowest lows.