But when, as a baby, Julien found himself unable to walk like other children, Paul refused to deal with his handicap and took refuge in his job as a cable car repairer and his service as a volunteer firefighter.

He shied away from his responsibilities, leaving the whole task of caring for Julien, who is confined to a wheelchair, to his wife Claire, who had become a mother too protective and fearful for her son's health.

At 17, Julien, now a difficult and stubborn teenager, becomes aware of life and dreams of adventures that are inaccessible given his disability.

He discovers that his father had been a good athlete 25 years earlier and had participated in an Ironman, an extreme triathlon race.

While a hint of togetherness, which had been so lacking all these years, begins to emerge between father and son, Claire fiercely opposes this dangerous adventure.