One day, an unprecedented treasure falls into the hands of Milo Thatch. He finds a mysterious diary, thanks to which his dream comes true - an exciting journey to Atlantis. A young scientist, along with a fearless team, sets off in search of an island that has long been considered a legend. But the hero does not even suspect that the terrible Leviathan is only the lesser of the evils that he will have to face on the way to the fantastic city.