The Lupin Collection, a set of mysterious treasures gathered by the legendary phantom thief Arsène Lupin, has been stolen by the Ganglers! The phantom thieves who fight to recover what they've lost. The police force who fight to protect world peace. Whose side are you on?! This is a question Equestria defenders must decide upon but what happens when the Mane 6 pick one side and the Princesses pick to side with the other.

(Set after keep Calm and Flutter on and the 14th episode of Lupinranger vs Patranger)