Insurgent made its box office debut this past weekend and Veronica Roth who is the mastermind behind the young adult series that this sequel and its predecessor are adapted from recently discussed the changes from the book to the film.

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Last month, the author took to her Tumblr and shared some insight on the "clear differences" between the book and the film.

"Insurgent, the book, has a complicated plot -- a lot of moving parts, a lot of ups and downs. That sort of thing can work in a book, but if it's translated directly to the screen, it makes for a messy, confusing movie," she explained.

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The author of the young adult series dished that changes that were made were neccessary and "they work."

Roth further revealed to Vulture on Tuesday more specifics about "the biggest change" in Insurgent.

The box that is in Jeanine's (Kate Winslet) possession is that major change. The box requires a special Divergent to open it, which is Beatrice "Tris" Prior (Shailene Woodley).

"The box. Yes. That was the biggest change, I think," Roth stated.

"So, just to back up a little bit, when I first learned that Insurgent was green-lit and that they were going to make it, it occurred to me that they were going to have to change a lot about it. The plot of Insurgent, more than the other books, is complicated," she added.

So much happens to all of the characters in the second book so Roth wasn't totally sure how the movie would translate given so much goes on, but those behind the movie came up with the box.

"So the good thing about it is that it gives Jeanine a lot of motivation for targeting Tris specifically, and for targeting Divergents generally," Roth said of the addition of the box in Insurgent.

"We get to know her reasons for doing that in the book, but those would be hard to make it onscreen. This gives us a visual way of understanding her motivation," she further explained.

Insurgent is in theaters now.