One of the most anticipated and contested sequels is the follow-up to Disney's smash hit "Frozen," the highest-grossing animated film of all time and an Oscar-winning hit. In fact, the plot to "Frozen 2" is already being speculated.

Few details are known about the animated film, like whether the same voice actors would return to play their characters again or a tentative release date.

While nothing has been confirmed with the plot of the next film, International Business Times suggests that "Frozen 2" may have a much darker theme than the first movie. Multiple movie industry news websites speculate that Disney could likely take a darker route with this sequel.

The basis of this sequel could be the original Snow Queen story. This idea of the second installment of "Frozen" could be adapted from Hans Christian Andersen's fairy tale, but this story is not all happy endings.

In his version of "The Snow Queen," Gerda, the main protagonist, serves as the character who must choose between good and evil. In the magical land where the story takes place, an evil troll creates a magic mirror that only shows the bad in all things. Gerta's friend Kai finds the mirror and becomes mean and cruel from gazing into the mirror repeatedly.

Kai is later kidnapped by the kingdom's queen and made to forget about Gerda. Gerda then goes searching to her friend and visits the Snow Queen's palace. She finds Kai and kisses him in order to break the Snow Queen's spell.

"The Snow Queen" is one of Andersen's most beloved stories and has been published all around the world.

In the first "Frozen," the Princess Anna is sent on an adventure to find and bring back her older sister, Queen Elsa, who has run away because of her magical icy powers. Chris Buck wrote and directed the modern classic.

However, Disney has yet to confirm the story of "Frozen 2" and whether main characters Elsa, Anna, Olaf and Kristoff will be returning to the second film.