Lupin walks into a job that's supposed to be simple, steal a fake gemstone, get paid, move on. Within minutes the job implodes into something nobody expected: a murder, an immortality riddle, and a woman who might actually be alive forever. This is Lupin at his best, where the con is never what it looks like and the real score is always hiding three layers deeper than the surface game.

A legendary aquamarine known as the Mermaid's Scale turns up at a secret underground auction, and the queen of the underworld, called the Bearslayer, pressures Lupin into stealing it for her. Lupin gets the stone but soon learns it is a forgery. The real Scale is tied to an unsolved riddle that points toward escaping death. Then the Bearslayer is found murdered, and her strangely ageless young aide, Misa, is abducted by an arms dealer named Himuro. Lupin and his gang race to find the secret of eternal life before it can be used to plunge the world into endless war. The treasure also has a personal pull for Lupin: it is the one prize his grandfather pursued but never stole. This adventure comedy was made as a TV special marking the franchise's 40th anniversary.