I couldn't fit everything into the space they allow for the description so let me better clarify what this story is about here without giving away any big spoilers :
- Kristoff proposes to Anna, causing everyone in the kingdom to rejoice. After the wedding date is set though, royal scholars are ordered to investigate the bloodlines of Kristoff and Anna as royalty, since it's tradition for scholars to review the bloodlines of the groom and bride before a royal marriage is held.
- Kristoff is found to not be of royalty, as expected, but that isn't a big problem. What IS a big problem is that when the scholars investigate Anna and Elsa's bloodline, they come to believe that Elsa and Anna aren't truly sisters.
- You see, Elsa is blonde. So blonde that her hair is arguably white, but Anna is a ginger, and undeniably ginger as well. Blonde and ginger are both recessive genes for hair color... Since the King and Queen before them had brown hair (mother) and blonde hair (father), the scholars come to the conclusion that Elsa is royalty, but that Anna is NOT royalty, and is only Elsa's half sister, since it's impossible for a completely blonde father and a brunette mother to have a ginger child.
- Elsa and Anna set out to prove that the two of them are indeed sisters and that Anna is royalty, with Kristoff and Olaf coming along to assist them. The gang is once again plunged into a very dangerous journey as they all try to help each other, but upon visiting the trolls for assistance, they all discover that the truth may be far worse then what they could have imagined, and the only place that holds the answer...
... Is the Southern Isles