Main characters Toothless and Hiccup go their separate ways in the third installment of the movie. Director Dean DeBlois revealed "How to Train Your Dragon 3" will see the return of the antagonist Drago Buldvist's and his ruthless plans. It was also disclosed that the movie will have the same ending with the book.

According to MovieNewsGuide, author Cressida Cowell stated that the movie will definitely have the same ending with the book. Even though many parts of the movie are different from the book, the author made sure that it will end identically. Director DeBlois also confirmed this by saying they are going to take the story back to the book, Hiccup reflecting and the dragons going away. He added, "Why and could they come back and the mystery of what all that is will be saved for the actual story."

"How to Train Your Dragon 3" will be about Toothless and Hiccup's character maturity. The plot will take place three years after the second movie. The incidents in the third installment are reported to be a tear jerking ones. Franchise Herald reported that fans might have the same sad feeling as to when they watched "Toy Story 3". The movie will focus more on Toothless independence rather that the both main characters.  

Christian Post also stated in their report that Toothless' struggle will be illustrated in the movie. Toothless wanting to become independent will affect his relationship with Hiccup. Also, the big fight between the dragons and humans will eventually take toll on their relationship. Furthermore, Drago will allegedly ask for vengeance after Hiccup and Toothless defeated him. Drago will separate the two and will pit them against each other.

Rumors about Toothless' love interest are also circulating. With all the heart-breaking confirmation about the movie like the separation of the two best friends, this will help the fans to make it better.

At first, "How to Train Your Dragon 3" was scheduled to premiere on June 17, 2016. However, the final release date for the movie was moved to June 29, 2018.