On a marché sous la Terre: Since the dawn of time, humankind has felt the need to explore, whether through terrestrial, subterranean, underwater, or space exploration. This film follows the attempt to connect the Fromagère chasm with the legendary Berger chasm, located in the Vercors massif. The exploration is undertaken by Cédric Lachat, a former world climbing champion, and David Parrot, a highly motivated speleologist. From preparation to success or eventual abandonment, this adventure explores the various facets of speleology: sport, science, and heritage.