GR5 revolves around four people in their mid-twenties who embark on the hiking trail Grande Randonnée 5, to commemorate their friend Lisa who went missing on the path five years before. Was there an accident? Or was she harmed? What happened to her ? With a diary revealing an act of desperation, her friends Zoë, Michiel and Ylena, decide to make the same journey, from the North Sea over the Ardennes, the Vosges and the French Alps to the Riviera. Coming together, the explorers all have different reasons for making the journey, but one common goal unites them - to find the truth about Lisa. The journey will change them forever: the heavy physical effort and mutual tensions lead to a confrontation, and a search to uncover the truth behind Lisa's mysterious disappearance.