Inspector Koichi Zenigata is visiting an airport in the frigid nation of Roviet when a devastating terrorist bombing occurs. In the chaos, he witnesses a man who appears to be his quarry, the notorious thief Lupin III, planting the explosives. However, when the determined Interpol officer manages to corner this suspect, the man vehemently claims his innocence, and Zenigata quickly realizes he is dealing with a fake. The situation becomes even more complicated when the real Arsène Lupin III arrives in Roviet with his partner Daisuke Jigen, intending to reach a mysterious island marked on a map in his possession. Now Zenigata finds himself caught between two identical thieves, but the Roviet secret police are far more interested in eliminating anyone wearing Lupins face than in making an arrest. The inspector, a man driven by justice, must capture both Lupins and unravel the truth behind the bombing plot.

As Zenigata pursues his investigation, the true Lupin is stopped by authorities while boarding a train but escapes with Jigens help. Meanwhile, Fujiko Mine infiltrates the upper echelons of Roviet society by posing as a singer, cozying up to Prime Minister Brelin. The fake Lupin strikes again, triggering another explosion that traps Fujiko in an unknown location. When the real Lupin and Jigen attempt to flee the country in a stolen car, they are intercepted by both Zenigata and the secret police. The fake Lupin once more causes a deadly explosion that wounds Zenigata in the lower abdomen. The injured inspector receives unexpected aid from Lupin and Jigen, who help him recover and advise him to focus on his own survival rather than the doppelgänger.

The false Lupin, now disguised as Fujiko, commits another attack during a ceremony for an international treaty between Roviet and the United States of Arca, apparently killing Prime Minister Brelin. However, it is later revealed that the slain official was a body double; the real Brelin had hired the fake Lupin to stage the bombing and sabotage the treaty. The prime minister hints at the existence of the same mysterious island that interests the real Lupin. Both the genuine Lupin and Zenigata converge on Brelins chalet, where the fake Lupin detonates explosives strapped to his own body, set to trigger after one hundred heartbeats. Working together, the lifelong rivals escape the blast as the impostor perishes. With Brelins deception exposed by the freed Fujiko, the real Lupin III reunites with his entire gang including Goemon Ishikawa XIII and departs for the mysterious island by plane. Unbeknownst to them, Inspector Zenigata secretly follows aboard another aircraft, determined to finally apprehend his nemesis. The story serves as a prequel to the feature film Lupin the IIIrd the Movie: Fujimi no Ketsuzoku.