There are few things more disappointing than your favorite book being adapted into an underwhelming movie. While some land wonderfully and are loved by fans, an unfortunate majority simply flop.

It seems that a lot of books are made into movies purely because they were popular and someone thought they would do well in the box office. It is rarely taken into consideration whether the story will work in the different medium and what changes need to be made in order for it to do so.

More important than just copying the text word for word is getting the overall themes down. Take The Lord of The Rings, for instance. The movies’ plot differs drastically from that of the books, yet they are considered some of the best book-to-movie adaptations out there. It’s because, despite the changes, the creators stayed true to the message Tolkien was going for.

A lot of times, a book will be either stretched out or compressed into a time period unfit for it. The Deathly Hallows, having been split into two parts, resulted in one being slow and empty, and another being so stuffed full of rapid action that you can barely follow what’s happening.

On the other hand, when a book adaptation is given just the right amount of breathing room, it can land wonderfully. Good Omens, by Neil Gaiman and Terry Pratchett, was adapted into a six episode mini-series, which was well-received by fans. One reason for its success is the novel has about ten main characters, all of which are vital to the plot. If everything had been forced into a two hour movie, most of the development and charm of the book would have been lost. A mini-series was able to portray every aspect of it.

Because many adaptations end up sacrificing important parts of the narrative, people often must already be familiar with the original work in order to understand what is happening. A good adaptation will not only be able to stand on its own, but also stay true to the themes the author intended, while still adding its own charm to the work.