Ørjan-Helmer Gundersen Solum (24) disappeared from a residential area in Arendal on 24 March last year. For several weeks, the police fumbled blindly. Then some earplugs were found close to a disused mine - filled with rubbish and water. Thus began one of the most extreme diving operations in Norwegian history. "The sledgehammer" worked for several hours smashing a safe in Rogaland. Can a mistake reveal the thief?