Only twice in my life have I enjoyed the film version of a story better than the original book. Let the Right One In is the second1.
Both the book and the movie are translated from the Swedish. They feature a young, social outcast of a boy who befriends, and eventually falls in love with, a mysterious girl named Eli who has just moved into his apartment building with her caretaker. Soon after she arrives, something starts killing people by draining them of all their blood. I'm not usually a vampire fan, but the movie avoids romanticizing vampires while still making the unsympathetic sympathetic.
The first two thirds of the book, however, read like the movie with extra padding. The only early difference isn't plot events, but rather the information given to the reader: It's made clear that Eli's 'caretaker' is a pedophile. He's only recently taken up with her, and feels like he's hit the jackpot, since she has the body of a child but a much older mind, which he uses to excuse his attraction.
Eli's gender ambiguity is also emphasized more.
Then we hit the two-thirds mark, and it's as if a fanfic writer went crazy with a what-if scenario2. In both mediums, Eli's caretaker's job is to kill people, drain them of blood, and bring it back to her so that she doesn't starve. He fails, is cornered by the police, and pours acid on his face to avoid identification. She finds him in the hospital, most of her strength gone, and ends up killing two birds with one stone by draining him dry. In the movie, he falls from the top floor of the hospital, and is gone. In the book, he falls from the top floor of the hospital - and lives…
…becoming a walking penis.
When they drag the corpse in off the street, its erection is mentioned. It turns out this isn't just a bit of macabre detail - it's foreshadowing! A big chunk of the rest of the novel is spent having the corpse stands up (apparently now one of the undead instead of a vampire), eat a hospital attendant, attack random people and roam through the wilderness, until it finally comes face to face with Eli.
At some point in there we also get a detailed play-by-play flashback as to how Eli (born male) was castrated and vamped at the same time. This flashback does not seem to inform anyone's motivation or any key plot points. It's just kind of… for folks who wanted a horrible castration scene3.
So, the big confrontation scene. One would expect a fight, right? Eventually. But first:
"What do you want?"
A hollow, rasping sound as the creature pressed out air and drop of yellowish, viscous liquid ran out of the double hole where the nose had been. A sigh? Then a damaged whisper… and one arm flinched quickly, cramplike,
baby movement
clumsily grabbed the shirt down at the hem, pulled it up.
Hakan's [the caretaker's] penis stood out from his body to one side, craving attention, and Eli looked at its stiff swollenness crisscrossed with veins and -
How can he… he must have had it the whole time.
Did this sound better in the original Swedish?
The caretaker then predictably tries to rape Eli. It's such a weird vibe in a book where the two main characters are underage, that the most emphasized and vibrant form of adult sexuality is literally a perversion, a monster. If I remember correctly, no other adult character is ever shown having sex, and none of their relationships are stable or loving (main boy's parents separated, only other couple is on-again-off-again and explicitly afraid of being a couple). If any of this had connected up with some broader theme, it might have gone somewhere.
As is… it felt like I was watching Sin City. Hey everybody, lets focus on castration that doesn't further the plot! Dicks! Older men with very young people and sexual attraction! Dicks!
Although hey, only one explicit castration vs. two, so we're still ahead of Miller's film (though I can't speak for the comic book)4.
But lest anyone paint both book and movie with the same broad brush, I can say the movie is fantastic, and definitely worth seeing.
1. The other one has absolutely no similarity to this case but, if you must know, is Jurassic Park. Because Chrichton essentially writes movie summaries anyway, and seeing dinosaurs running around eating people onscreen could be improved only if someone armed the velociraptors with automatic weapons and sent them off to fight zombies.
2. Although it's more correct to suppose that fanfic writers got hold of the movie, since the book is the original work. But fanfic writers are rarely big fans of reducing the cannon, and the movie is far more minimalist than the book.
3. It also, along with a few other scenes, transforms what in the movie was a transgendered character handled with a light touch into more of an Othering. Eli is still sympathetic, but there's a lot of the schoolboy fascination with the castration, etc.
4. I love the visual overblown noir look of Sin City and The Spirit in the same way that I love Lovecraft's overblown prose, and I wish that Miller would do a movie in that style in which the women were not there just props, because then I might actually enjoy it.