A message appears in the morning paper reading "Lupin Is an Idiot". Lupin says it is a secret code from his late grandfather telling him it's time to reclaim Lupin the First's prized diamond. But the gem is locked away in police headquarters, encased in a globe of liquid. Should a single vibration touch the liquid, the entire facility will explode. To make matters worse, Lupin is tricked into accepting a challenge from the police chief. If he does not steal the diamond within one week, he will spend the rest of his life in prison