The movie tells the story of Melos, a Greek country man that gets arrested and accused of conspiracy against the king. He gets three days to travel to his sister's wedding while Selinentius (Selinae), a genius sculptor that Melos just met stays as a hostage.

After Inspector Zenigata is reassigned from the Lupin case and grows despondent, master thief Lupin the Third decides to help him get his old job back, teaming up with the old man to destroy the international weapon smugglers Shot Shell. Together with Lupin's long-time partners in crime, they steal a nuclear Russian submarine and enlist the help of a nuclear physicist named Karen, who keeps suspiciously eyeing Lupin's partner Jigen. If that weren't enough, Zenigata's Interpol successor is an assassin who aims to pick off the Lupin gang one by one.