The notorious thief Lupin the 3rd embarks on a daring mission to retrieve the elusive Trick Diamond, once concealed within Spain's Sagrada Familia cathedral. Following a cryptic message from his late rival, Mark Williams, Lupin faces a challenge to return five stolen treasures to their rightful places within a strict deadline. Failure to do so will jeopardize his quest to locate the Trick Diamond. With the enigmatic Fujiko, Mark's assistant, harboring hidden truths and the menacing Mafia boss Ivan 'Rats' Crockovich hot on their trail, Lupin must outsmart both adversaries to secure the prized gem and safeguard his crew from impending danger.