Adapting a book to a screenplay almost always involves change. To see how various screenwriters tackled this problem, look at the classic science fiction story “I Am Legend.”
“I Am Legend” with Will Smith tackles Richard Matheson’s classic story about a solitary man left in a world full of vampires. Read the book version first and then examine the various film adaptations that include Will Smith’s latest version along with “The Omega Man” with Charleton Heston. By studying both films, you can see how screenwriters tackled the problem of adapting a novel into a movie.
Since more people are probably familiar with the Will Smith “I Am Legend” version, start with that one first. One major change between the book and the movie is that in the book, the hero is just an ordinary man. In the movie, Will Smith is a virologist, trying to find a cure for the deadly disease that has turned people into flesh-eating zombies. (In the book, the villains are actually vampires, but in the movie, they seem like a curious combination between vampires and zombies.)
Giving the hero a specific occupation that’s related to the problem (the virus turning people into zombies) makes the movie stronger. Rather than a hapless hero trapped in a world he can’t control, the movie gives the hero a goal and control over his situation. Make the hero connected to the problem as much as possible and in this respect, the movie version does a great job making Will Smith capable of controlling his situation and actively trying to do something about it, which is to find a cure.
Changing the villains from vampires into zombie-like creatures in the movie is more for visual effect. Watching a vampire walking around isn’t as visually interesting as seeing a zombie running after you. In this case, the change is more for visual effect than for strengthening the story.
In the book, the head villain is a vampire that used to be a neighbor of the hero and car pool with him. In the movie, the head villain is just a tough zombie. In this case, the film severs the connection between the hero and the villain, making the movie version of the villain just seem like a guy who hates the hero for no apparent reason.
The movie version did have an alternate ending that apparently didn’t play out as well for audiences. In this alternate ending, the head villain is trying to get back a female zombie that Will Smith is experimenting on. This gives the head villain a much stronger motivation to attack the hero rather than just attack him just to make his life tougher.
The ending of the book has the vampires finally capturing the hero and executing him. In the movie, the villains corner the hero as he finally discovers a cure and kills the zombies with a hand grenade. The movie version is more visually appealing and directly places the hero and villain on a collision course where only one can win.
The basic three changes that the movie made to the book are these:
- Give the hero more control over his situation and a motivation to survive.
- Fail to explain the head villain’s connection to the hero.
- Make the ending more visual with a direct confrontation between the hero and the villain.
Overall, “I Am Legend” the movie strengthens the book version and makes it stronger and more visually appealing. The book version, if filmed, is simply a much weaker story visually. The real strength of the book version is the anguish of the hero as he realizes that he’s trapped, outnumbered, and eventually doomed. That simply doesn’t work in a film where we need a hero to be proactive and not just wait around to die.
“The Omega Man” with Charleton Heston more closely follows the book version of “I Am Legend” by placing an unknown hero in the middle of a world where vampires rule and he’s the only survivor for some odd reason. The ending of “The Omega Man” is also more closely related to the book than the Will Smith movie version.
In both movie versions, the story ends with a touch of hope. In the book version, the story ends with the hero being defeated. Watching a hero lose isn’t usually a formula for success in movies, so that explains why both film versions changed the ending.
In case you want to practice your screenwriting skills, take any public domain story (such as any of the classics like Shakespeare’s plays or novels by Charles Dickens) and adapt those stories either as a faithful adaptation or as an interpretation of the story in modern times. By trying to adapt a story, you’ll see the differences between a novel and a screenplay, and what elements of a screenplay you need to keep even at the sacrifice of the original story.