Lupin embarks on a quest for a long-lost treasure amassed by the legendary thief Harimao during World War II, a fortune valued in the billions. His scheme to deceive retired British spy Sir Archer for the treasure's whereabouts is foiled when Archer joins the pursuit. Lupin must now join forces with his previous target to outsmart a new adversary coveting the riches. Meanwhile, Zenigata is hot on their trail, determined to capture the group once more.