This four-part documentary series, adapted from Eric Lemasson's book, explores one of the biggest criminal mysteries of the last twenty years, following the trail of the missing family, from Normandy to the north of Scotland, via Saint-Malo and the Isle of Man. The investigation links this family drama to the assassination, in 2001, of the emblematic leader of a small traders' union, the CDCA, by professional killers. The tragic story of the doctor who decided to drop everything to change his life intersects with the mafia nebula surrounding this "anti-system" union.