(Spoilers in this post are hidden with spoiler tags.)

What made Project Hail Mary so good? Among other reasons, it’s because the science drove the story, instead of the other way around.

Character-driven stories and hard sci-fi might take up opposite positions in the ancient battle of “people vs. things”; but when they work, they work for fundamentally the same reasons.

In mediocre “people”-focused stories, the plot dictates how characters behave. In great people-focused stories, the characters decide what happens.

In mediocre sci-fi, the plot dictates what science and technology can do. In great sci-fi, the science and technology constrain what routes the plot can take.

When the internal logic of the world makes sense, and everything fits, it satisfies “thing”-brained people in the same way that deep three-dimensional characters satisfy people-brained people. And when the science is inconsistent, it bugs thing-brained people in the same way that it’s no fun to watch the protagonist make stupid out-of-character decisions in service of the plot.

Project Hail Mary is an excellent example of what I mean by this. The central plot of Project Hail Mary naturally fell out of Andy Weir’s daydreams about rocket science. (spoilers for the first 10 minutes of the film)1 The rocket equation dictates that the amount of fuel you need grows exponentially with how fast you want to go (by which I mean literally exponentially, not just “a lot”). So he thought, wouldn’t it be cool if we had a fuel source that could directly convert matter into energy? Maybe it could be some sort of microbe that absorbs sunlight. But we’d have to make sure none of the microbe gets onto our sun because that would be disastrous. Oh, there’s the story!2 If he didn’t care about making the science accurate, he never would’ve thought up the plot in the first place.

(spoilers for midway through the film) Rocky’s biology was determined by the properties of his home planet. Rocky comes from a planet orbiting 40 Eridani A3, which orbits very close to its star. What properties would that planet need to have to support life? It would need a heavy atmosphere or else the air particles would fly away. That means light wouldn’t reach the surface, so intelligent life wouldn’t be able to see; therefore they’d probably use echolocation.4 The reason Rocky echolocates isn’t that Andy Weir thought it would be cool; his echolocational capabilities are an implication of the environment he evolved in.

The science doesn’t always have to make sense. Firefly doesn’t even attempt to explain how any of the futuristic technology works, and it’s one of the best shows ever made. But science-driven stories light up my brain cells in a way that other stories don’t.

Science-driven plot isn’t limited to science fiction. Brandon Sanderson is the prime example of a fantasy author who writes like this. He even has a system of Laws of Magic. The first two laws state:

Sanderson’s First Law: An author’s ability to solve conflict with magic is DIRECTLY PROPORTIONAL to how well the reader understands said magic.

Sanderson’s Second Law: Limitations > Powers

In other words, don’t shoehorn in some magic to make the plot go where you want. Magic should impose limitations, and those limitations should guide where the plot goes.

(Annie from Misery didn’t like plot-driven magic, either. She was just as rational and level-headed about this as I am.)

Science-driven plot and character-driven plot are fundamentally the same phenomenon: the plot emerges organically instead of being forced.

Let’s talk about Breaking Bad, which is my favorite TV show. The primary refrain in the writer’s room was, “Where is Walt’s head at?”5 The refrain wasn’t, “What awesome cool plot twist should happen next?” To figure out the plot, they took an intriguing agentic character (Walter White) and thought about what choices he would authentically make.

Interesting characters make the plot interesting. If you simply ask “what would Walter White do in this situation?”, the answer will be that he does something interesting (read: crazy). There’s no need to shoehorn anything. Similarly, if you come up with a sufficiently interesting scientific premise, the story can write itself.

Notes

  1. I also read the book, but I don’t know how to convey how much of it is spoiled by this anecdote. Whatever fraction of a book is proportional to the first 10 minutes of a movie, I guess? ↩

  2. Critical Drinker After Hours (2026). Drinker’s VIP Lounge - Andy Weir [Video]. Timestamp 35:53. ↩

  3. except after Project Hail Mary was written, new research came out showing that what we thought was a planet was actually just fluctuation in solar output, and probably the planet doesn’t exist ↩

  4. Penguin Random House (2026). Andy Weir on Balancing Science and Story [Video]. Timestamp 3:34. ↩

  5. Dixon, K., et al. (2009–2013). Breaking Bad Insider Podcast. Various episodes.

    (“various episodes” is code for “I listened to the podcast a long time ago and I don’t remember which episodes they talked about this in”) ↩