Don Dolune, a former associate of Lupin, gives Lupin half of a diamond called the Twilight. By finding the other half of the diamond, it will allow Lupin to access a fantastic treasure. Lupin and Jigen travel to Morocco with some interference from Inspector Zenigata. The two find a great deal of civil unrest in Morocco as a tribe known as the Gelts are seeking to restore themselves to power. Things become complicated when Lupin falls for Lara, one of the Gelt rebel leaders. Lupin is followed by a group of assassins, headed by the twisted male whip-wielding Sadachiyo, who is seeking the treasure of the Twilight for the head of a secret society.