‘Race Across The World changed my relationship with grief’

After Mark’s wife Julia died, he and his sister-in-law Margo went on Race Across The World together (Picture: BBC/Studio Lambert)

On her very last day before Julia died, she asked her husband to keep a promise. Could he become best friends with her sister, Margo?

It was a fairly tall order. For the entire time Mark and his wife were married, he’d never seen eye to eye with her sister. Margo is loud, vivacious, walks into every room and has swiftly spoken and befriended everyone in there. Mark is bashful, gentle and quiet – their polarising energies just never quite connected.

But Julia knew that without her, Mark would need Margo more than he knew.

Three years later, Mark and Margo find themselves taking extreme lengths to fulfil Julia’s wish, sprinting from the glorious streets of Palermo, Sicily, to a remote village in Mongolia without credit ca...