Frozen 2: A Blast From the Past

SUMMARY: A mysterious stranger from Elsa's past comes back to take over Arendelle and wants Elsa to join him/her. Meanwhile the prince and princess of Corona visited Arendelle to congratulate her and befriended Anna, Olaf, Sven, and Kristoff along the way but later on got captured by the stranger, now it's up to Rapunzel and Elsa to save them or is it the other way around?