This 3-part series is an account of Perrine Fages’ attempt to complete the Arch-2-Arc challenge. In this ultra-triathlon, solo athletes are expected to link the London’s Marble Arch and Paris’ Arc de Triomphe. The race starts with an 140-kilometre run from Dover on the Kent coast, then the athlete has to do a cross-Channel swim (shortest possible distance is 33,8 km) to the French coast, and then the challenge is finished with a 289,7-kilometre bike ride from Calais to Paris.