January 28th 1968: the submarine La Minerve disappeared into the waters of the Mediterranean. In spite of the extensive search organized by the French Navy, the craft and its 52 crew members were never found, thus laying the ground for one of the greatest mysteries in French naval history. Summer of 2019: more than a half century later, the search resumes and turns out to be the largest underwater investigation ever carried out by the French forces. Through archival and 3D images, alongside light re-enactments, this documentary narrates the incredible adventure of past and present searches, showing elements of the unfinished investigation of 1969 and the perseverance of the commander's son, Hervé Faure. Le Fantôme des Abysses also features key moments such as the first days of the investigation of Ifremer, the search conducted by the Seabed Cosntructor's team, and finally the discovery of the wreck