Frozen II: Dangerous Secrets: The Story of Iduna and Agnarr, by Mari Mancusi, is a tie-in novel to Frozen II.
Sixteen-year-old Iduna harbors a dark secret. On the surface, she is an Arendellian village girl, an aspiring inventor, and the best friend of Prince Agnarr, but she is also secretly Northuldra.
Ever since the day the forest fell, Arendellians have despised and distrusted Northuldra with a vengeance. No matter that the Northuldra—along with some of Arendelle's own—have been trapped in the Enchanted Forest behind an impenetrable wall of mist since the day of the battle.
Iduna doesn't know why the mist refuses to part, or why it descended to begin with. The only clear thing is that she must keep her identity from everyone, even Agnarr. Her life depends on it.
Fortunately for her, Agnarr doesn't know that Iduna is the Northuldra girl he saw seemingly flying on a gust of wind all those years ago, the day of the celebration turned disaster. The day Agnarr lost his father, the king. The day Agnarr himself almost died. What Agnarr does know is that Iduna is a true ally in the face of his royal responsibilities and the expectations of an overbearing council and a well-meaning regent who will rule in Agnarr's place until he turns twenty-one and assumes the Arendellian throne.
As Iduna and Agnarr grow ever closer, however, friendship is no longer enough. If only falling for each other didn't mean risking their futures: Iduna's as a hidden-in-plain-sight citizen of Arendelle, and Agnarr's as imminent king.
But for a chance at true love, the risk might be worth taking.
This book contains examples of:
- Arranged Marriage: There are two attempts to set up marriages between royals for political reasons.
- The council wants Agnarr to marry the princess of Vassar, but he's already in love with Iduna.
- It also turns out the marriage of Rita and Runeard was arranged. It did not end well.
- Better as Friends: Agnarr and the princess of Vassar decide this and build a trade agreement without getting into marriage.
- Childhood Friend Romance: Agnarr and Iduna. They start the romance in their teens.
- Continuity Snarl: The horse Iduna gets from the farmer is named Havski, though for some reason she starts calling it Kiekk a few lines later. This is meant to be the same horse Anna uses in the franchise.
- Destructive Romance: Runeard's arranged marriage with Rita more or less ruins her life. While he initially attempts to impress her with royal gifts, he refuses to give her what she really desires: love and freedom. This gets so bad that she flees and seeks out the trolls to get her memory of the marriage wiped.
- Entitled to Have You: Johan assumes Iduna will be down to marry him after years of their professional partnership in the windmill production business. When she isn't, he lashes out at her and fires her on the grounds that he's unable to 'go back to talking about wind' after this rejection.
- Evil All Along: In typical Frozen fashion, there is a twist villain in Vassar's King Nicholas, who fakes Northuldran attacks upon the defenseless kingdom of Arendelle so he can insinuate himself with promises of military aid and establish an alliance by marrying his daughter Runa to Agnarr, securing his own power.
- Fantastic Racism: Iduna has to hide the fact that she's a Northuldra in Arendelle or else she's sure they will kill her. In part thanks to Runeard constantly blaming magic for things going wrong, the Arendellians fear magic as well as the Northuldra themselves, always blaming them for things going wrong.
- Happily Adopted: Iduna was actually born to a different Northuldra tribe, but was adopted by Yelana's after hers was ravaged by invaders.
- Jerkass: Johan, Iduna's boss whom she basically taught how to build windmills, fires her for rejecting his marriage proposal.
- Mythology Gag:
- Iduna reads about Hundrefolk in a book, same creatures Elsa and Anna meet in another spin-off Frozen book, Forest of Shadows. A man named Soreson is mentioned, too. But in FOS he mentions he was friends with Iduna; here they never even meet.
- Lord Petersen also serves as Elsa's regent in the A Twisted Tale book Conceal Don't Feel/Let it Go.
- Reasonable Authority Figure: Lord Petersen recognizes young Iduna as a Northuldra but covers for her, acknowledging that she's an innocent child.
- Origins Episode: This book tells the backstory of Agnarr and Iduna after they were first introduced in Frozen. It covers Agnarr and Iduna's lives from the mist falling to their deaths.
- Parental Abandonment: Rita left Arendelle to get away from her loveless marriage to Runeard. She was afraid to take Agnarr with her for fear that Runeard would hunt them down and asked the rock trolls to take away her memories so that she could forget.
- Passing the Torch: The stuffed penguin Sir Jorgenborgen was made by Queen Rita for Agnarr, Gerda saved it from King Runeard and gave it to Iduna then Agnarr gives it to Elsa to cope with her and Anna's separation, having cuddled with it to endure his father's oppression in the past.
- Poor Communication Kills: In this book, Agnarr separates Elsa and Anna because he assumes that the cause of the accident where Elsa seriously injured Anna was that Elsa lost control of her powers after becoming too joyful. In the original movie, it's shown that the cause wasn't Power Incontinence, but simply that Elsa misaimed. She tells Agnarr that it was an accident, but not how it happened.
- Right for the Wrong Reasons: After Iduna reveals the guilt of King Nicholas, he claims she's a Northuldran. He's actually right that she is, but his reason for making the claim wasn't based on fact, but to draw attention away from himself.
- Secret Room: Iduna and Agnarr find the same secret room in the library that Elsa and Anna find in Forest of Shadows (and in the deleted scene from Frozen II).
- Unperson: After his wife Rita left, Runeard threw away all her possessions and would banish anyone who spoke her name.
