"Lupin III: Seven Days Rhapsody" is a television special within the Lupin III franchise, centering on the exploits of the master thief Arsène Lupin III and his companions. The narrative begins with Lupin successfully stealing a valuable artifact, the "Golden Violin," from a high-security auction. However, his victory is short-lived as he is immediately ambushed by a mysterious woman named Maria, who steals the violin from him. Maria reveals that she is working under the orders of a powerful crime syndicate, and she demands Lupin's assistance in retrieving a second artifact, the "Silver Violin," within seven days. Failure to comply would result in the death of Lupin's close ally, Daisuke Jigen.

Lupin, along with Jigen, Goemon Ishikawa, and Fujiko Mine, embarks on a high-stakes mission to locate the Silver Violin, which is hidden in a heavily guarded mansion. The group faces numerous obstacles, including rival thieves, elaborate traps, and the relentless pursuit of Inspector Zenigata, who is determined to capture Lupin. As the deadline approaches, tensions rise within the team, particularly between Lupin and Fujiko, whose loyalties are tested by the unfolding events.

The story delves into themes of trust, betrayal, and the complexities of relationships within the criminal underworld. Maria's true motives remain ambiguous throughout the narrative, adding layers of intrigue and suspense. The climax unfolds in a dramatic confrontation at the mansion, where Lupin and his team must outwit both the syndicate and Zenigata to secure the Silver Violin and save Jigen. The resolution ties together the various plot threads, revealing the interconnected fates of the characters and the consequences of their actions.

The special maintains the signature blend of action, humor, and suspense characteristic of the Lupin III series, while introducing new dynamics through Maria's character and the time-sensitive nature of the mission. The interplay between Lupin's resourcefulness, Jigen's loyalty, Goemon's discipline, and Fujiko's unpredictability drives the narrative forward, ensuring a fast-paced and engaging storyline.