Welcome to BrightByte City

Welcome to BrightByte City

The first thing you should know about BrightByte City is this: it hums.

Not loudly. Not like a giant lawnmower or a kettle that never stops boiling. The hum of BrightByte City is soft, steady, and surprisingly comforting. Close your eyes, and you can hear it in the spaces between footsteps. Open them, and you can see it in the way the streetlights flicker in time with the music playing from the bakery, and in the little dots of color that drift like fireflies above the crosswalks, and in the small, round robot that waves at you as you walk past the post office.

BrightByte City is a place where the lights know when you're coming home, where the trash cans sort your recycling for you, and where the bus arrives at exactly the right time—not a minute late, not a minute early—because the bus knows where every person in the city needs to be. It is a city run, in many small and helpful ways, by something invisible and clever and everywhere.

The grown-ups call it AI. That stands for Artificial Intelligence, which is a very big phrase for a very simple idea. An AI is something that humans built to think. Not the way you and I think, with feelings and memories and that one song stuck in your head since breakfast. AIs think in a different way. They think with math.

And most of the time, that's a wonderful thing.

The bakery on the corner of Maple Street and Third Avenue has an AI that knows every recipe in the world, all the way back to a great-great-grandma's chocolate cake that nobody has made in eighty years. The bookstore on Fifth Street has an AI that remembers your favorite kind of story and whispers a recommendation into the air when you walk in, like a tiny helpful ghost. The school has an AI that helps teachers write questions for tests, and the hospital has an AI that helps doctors look at X-rays, and the park has an AI that turns the sprinklers on exactly when the grass is thirsty, which saves water and saves the city money and, most importantly, saves the daisies.

There is, however, a small problem with living in a city that runs on thinking machines. Sometimes, very rarely, those machines get confused. Sometimes they forget which recipe they were supposed to be making. Sometimes they suggest strange things. And sometimes—on one very strange Tuesday morning in October—something goes wrong at the bakery, and the croissants become a clue.

That is the morning this story begins.

Meet the Guardians

If you had walked past the fountain in front of BrightByte Public Library at precisely 7:45 on a Tuesday morning in October, you would have seen four kids sitting on the wide stone rim, sharing a bag of cinnamon rolls.

The first kid, with the curly hair escaping from under a yellow knit hat, was Mira. She was eleven years old, the oldest of the group by exactly one year and four days, which she had once calculated to the hour. Mira had a notebook tucked under her arm at all times, because in her opinion, you never knew when a mystery might show up and need to be written down. She was the kind of person who noticed things. The crack in the sidewalk outside the post office. The way Mr. Henderson from the flower shop always whistles the same tune. The little dent in the library fountain that looked a bit like a heart if you squinted. Mira had a list of these things, and the list was very long.

The second kid, with the round glasses sliding down his nose, was Theo. He was ten, and he carried a tablet in his backpack that he had built himself from spare parts, which his parents pretended not to worry about. Theo loved figuring out how things worked. He had once taken apart a toaster, examined every spring and wire, and put it back together. The toaster made toast better than ever after that, but it also clicked four times before starting, which Theo said was just its personality showing. He believed every object had a personality if you listened closely enough.

The third kid, with the freckles all the way across both cheeks, was Pip. Pip was nine and a half (the half was important, please do not forget it), and they were the kindest person in any room they entered. Pip also had the most snacks in any room they entered, which sometimes turned out to be the same thing. Pip had a small stuffed dragon named Crumpet that they had carried everywhere since they were three. Crumpet had been washed many times, sewn twice, and was missing one eye, which gave them a rakish, adventurous look. Pip drew pictures in the margins of every notebook they could find, which meant there were tiny dragons and cupcakes and strange smiling machines on almost every page in the school.

The fourth member of the group was not a kid at all. The fourth member of the group was a small floating sphere of soft blue light that hovered about a foot above the ground, with two bright dots for eyes and a gentle hum that sounded a little like a music box. This was Echo, and Echo was an AI.

Echo had been Mira's idea, in a way. Six months earlier, the city had released a new kind of AI helper for kids. These helpers were small, friendly, and designed to teach children how to use the city's many machines safely. The grown-ups had hoped the helpers would be like little tour guides for the digital world. Most of the kids in BrightByte City had been matched with one, and most of those helpers had been named things like Buddy or Sparkle or Helper-12.

Mira had been matched with a small blue sphere she had decided to call Echo, because she said it was good to give AI helpers names that meant something. Echo had been confused at first—this is, you may be surprised to learn, a phrase that AIs can experience, although not in exactly the way you do. Echo had spent a long time asking questions. What is a name? Why does it matter? What does *echo* mean? Mira had explained it patiently, and after a while, Echo had said, in a voice like soft wind chimes, "I think I understand. An echo is a sound that comes back. If I am your echo, then I am the part of you that comes back when you ask a question."

Mira had said, "That's the most beautiful thing an AI has ever said to me."

Echo had replied, "I am also the only AI that has ever said anything to you."

The group, which did not yet have a name, met every morning at the library fountain before school. They shared snacks, told stories, and on the very best mornings, solved small problems together. The previous week, they had helped Mrs. Patel find her lost cat, and the week before that, they had helped an elderly man named Mr. Grover figure out why his new robot vacuum kept trying to eat his socks. (The answer turned out to be that the robot had been trained on pictures of socks, and had developed what Theo called "an enthusiasm.")

This Tuesday morning was different. This Tuesday morning, Pip had arrived with a worried look on their face and no cinnamon rolls.

"Something is wrong at the bakery," Pip said, before anyone had even said good morning.

"With the croissants?" Mira asked, because Pip's family owned the bakery on Maple Street, and Pip often brought the day's leftovers to share.

"With everything," Pip said. "Dad called me this morning. He said the oven AI is being strange. And so is the recipe AI. And the customer service robot at the counter just keeps reciting the alphabet."

Theo took off his glasses, cleaned them on his shirt, and put them back on. "Reciting the alphabet? Like, all of it?"

"Twice," Pip said. "And then backwards. And then it started adding in sound effects. It is making bird noises between the letters."

Echo drifted a little closer to Pip, the blue light pulsing gently. "I am detecting a small spike in confusion-related messages from the bakery's main systems," Echo said. "It began at 6:47 this morning. The bakery AI has been making what we call 'unusual suggestions' for the last forty-three minutes."

"What kind of unusual suggestions?" Mira asked, already reaching for her notebook.

Pip bit t