A month has passed since the tragedy in London, and preparations for a peace ceremony are underway. To celebrate Cardia Beckford's wish, Arsène Lupin is planning a party for her, but his search for the perfect gift gets complicated when a valuable jewel goes missing and he's implicated in the theft. With Lupin imprisoned, his friends team up with Cardia and a new ally to clear his name and uncover the true identity of the thief.