Will Self concludes his 50 kilometre circumnavigation of the Large Hadron Collider at CERN just outside Geneva - entirely on foot. Following the course of the Collider through the French and Swiss countryside, Will stops at regular intervals to descend to the tunnel below and view the experiments. As Will gets close to completing his circuit, he visits Voltaire's chateau and an abandoned CERN experiment. The excursions put Will in a pensive frame of mind as he heads towards Geneva Airport. Producer: Laurence Grissell.