Deep in a mysterious Crimean bay lies the "Som"-one of the first submarines of the Ukrainian Black Sea Fleet. Nearly a century ago, its crew scuttled it to keep it from falling into enemy hands during the early days of Ukraine's struggle for independence. Onboard the "Som" rests a true treasure-one that could uncover long-hidden secrets and reshape our understanding of a heroic chapter in history. But what creature guards the entrance to this bay? And who else is after the underwater treasure, hoping to claim it-and erase the truth? Determined to find out are our fearless treasure hunters: two boys from Kyiv, Danylo and Bohdan, their friend Halka from Poltava, and the team's unlikely but loyal member-a battle-hardened African ostrich named Football.