In the fictional kingdom of Vespania, Princess Mira Vespaland is forced onto the throne after her mother's suspicious death and her brother Gill's suicide, two deaths she suspects were no accident. A goodwill visit to Japan puts her in contact with her lookalike, Ran Mouri, and the two swap places just as master thief Lupin III arrives chasing a mineral with stealth properties tied to the crown. Conan Edogawa, dragged into Vespania alongside Ran, Kogoro Mouri, and Lupin's crew, has to untangle a royal murder plot before Mira's coronation. This TV special crosses over Detective Conan with the Lupin III franchise.