A murder takes place in Saint Jean Pied de Port (France), and so the Gendarmerie's investigation begins. The next day, another murder is committed with identical characteristics in the Roncesvalles pilgrim shelter . The conclusion is that a serial killer is on the loose on the Camino de Santiago. More crimes are expected and Captain Roncal of the Guardia Civil is named to solve the case. This detective thriller unfolds along the centuries-traveled pilgrim route, the Camino de Santiago, which in the end becomes a rite of passage for the protagonists themselves.