The Wiring Diagram

The model skeleton hung from a coat hook on the garage wall, a plastic thing from a costume shop with a missing left thumb.

"Okay," Maya said. "The rule is, every string goes from where the signal starts to where it lands."

Soren had the yarn sorted into piles. Red for the heart, blue for the lungs, yellow for the nerves. He was very serious about the piles.

"Brain first," he said. "Brain talks to everything."

They ran yellow yarn from the skull to the arms, the legs, the plastic ribs. Maya taped the ends down with masking tape and a lot of impatience.

"Heart next," she said. Red yarn, skull to chest, chest to everything. Then blue for the lungs. Then a green one Soren insisted on for the gut, because he had read that the gut sends more messages up to the brain than the brain sends down.

"That can't be right," Maya said.

"It's right. I checked twice."

She let it go. The skeleton was starting to look like a puppet caught in a spider web. Every important part had strings coming out of it, running to every other part.

Except one.

Maya stepped back and looked at the whole thing, the way she looked at a jigsaw when a piece felt wrong before she found it.

"The bones don't have any strings," she said.

Soren checked his piles. "Bones are the thing the strings are taped to. They're the frame. You don't wire the frame."

"But every part sends something." She tapped the plastic thigh bone, the big one. "This is a part. Why doesn't it send anything?"

"Because it's a coat rack," Soren said. "It holds you up. It stores calcium. That's the job."

"That's a boring job."

"Not everything gets to be exciting, Maya."

She frowned at the thigh bone. It was the biggest bone on the whole skeleton and it just sat there, holding up other people's strings, sending nothing to anyone.

She pulled out her phone.

"What are you doing?"

"Checking if the coat rack is really a coat rack."

Soren went back to taping while she read. He liked the taping. He was halfway through a blue string when Maya went quiet, and he knew that kind of quiet, so he stopped and waited.

"Soren," she said. "Bone makes a hormone."

"Bones store hormones. Calcium and stuff."

"No. Makes. It has a name." She read it slow. "Osteocalcin. The bone builds it and pushes it into the blood."

Soren put the tape down. "Pushes it where?"

Maya scrolled. Her mouth moved a little while she read, and then she looked up at him with an expression he did not have a word for.

"The pancreas," she said. "It talks to the pancreas. It tells it to handle sugar. Bone helps run your blood sugar."

"That's the pancreas's job."

"They do it together. There's a string, Soren. Bone to pancreas." She grabbed the yarn pile and pulled out a length of orange. "We need orange."

Soren took the phone from her, because he had to see the words himself before he believed a coat rack was sending mail to the pancreas. He read it twice, the way he read everything twice. Then a third time.

"It goes to the brain too," he said quietly.

"What?"

"The same hormone. Osteocalcin. It reaches the brain. It's tied to memory." He looked up. "Maya. Your bones are part of how you remember things."

They both looked at the skeleton on the coat hook. The dumb plastic skeleton with the missing thumb, hung up like a jacket, holding everyone else's strings.

"So when I'm running," Maya said slowly, "and my legs are pounding the ground, the bones feel it. The pounding."

"Bone senses load. Yeah. That's real. It knows when it's being used."

"And it makes more of the hormone when it's being used." She was pulling yarn faster now, orange and a purple one for the brain, and a second orange because one wasn't enough. "So my legs pounding the sidewalk is a message. To my pancreas. To my memory. To my mood, it says here, it changes your mood."

"Run a string," Soren said.

She ran the orange from the big thigh bone to the plastic belly where the pancreas would be. Soren ran purple from the same thigh bone up to the skull. Then they stood there and it wasn't enough, because now they could see it, the bone wasn't at the end of anything. It was a sender. It needed strings going out in every direction, same as the heart, same as the brain.

"It's not the coat rack," Soren said.

"It was never the coat rack." Maya was already cutting more yarn. "It's another brain. A slow one. It's been talking the whole time and nobody wired it up."

Soren picked up the green gut string he'd been so proud of, the one that surprised everybody, and he laid it down next to the orange bone string, and the orange one was bigger news and he didn't even mind.

"Every kid who was ever told to sit still," Maya said. She wasn't cutting anymore. She was holding the scissors and looking at the thigh bone. "Sit still, stop moving, stop running around. And the whole time the moving was the message."

"The bones were trying to send something," Soren said.

"And you can't send it sitting still."

He wrote it down then, the word osteocalcin, and under it he drew the thigh bone with lines coming off it in a fan, to the belly, to the skull, out past the edge of the page where he ran out of room and kept the lines going anyway into the margin.

Maya taped the last orange string to the pancreas and stepped back and the skeleton didn't look like a puppet anymore. It looked like a switchboard. Every bone a station. Every step a call going out.

"We're going to need more yarn," she said.

Soren looked at the two piles they had left, the small orange and the almost-gone purple, and then at the skeleton, at all two hundred and six bones of it, each one waiting for its strings.

He reached for the scissors.