Lupin and company are sneaking inside a room with a vault in it. After breaking into the vault, they all begin to steal thousands of wonderful diamonds. But a fire breaks loose in the room, and they narrowly escape with only one diamond but without Fujiko. Lupin immediately investigates the incident and soon finds that the diamonds are all fakes and part of a plan to make the cost of the diamonds rise. What Lupin doesn't know is that the owner is telling Zenigata that Lupin burned the diamonds to increase their value. Lupin will not let this go unanswered. What will Lupin do? Where did Fujiko run off to?