Rocky’s eyes glimmered, but he kept his chin up. “It’s okay,” he said. “I want to know.”
I took a deep breath. Then I continued, filling in Dr. Chatterjee, starting with when Patrick had interrupted me in the barn. The acrid smell on the wind. The hammering noises and screams carrying over from the McCafferty place. When I got to the part about Mrs. McCafferty in the grain silo, JoJo buried her and Bunny’s faces in her brother’s chest. I described climbing to the top of the water tower and the sight waiting for us, Hank blown wide open, releasing spores to the wind.
Rocky held his sister tight. He didn’t sob, but tears spilled down his cheeks. Alex put her arms around him from behind, holding him even as he held JoJo. My face burned as I related details of Hank’s death—I knew as well as anyone that a child should never have to know too much about that—but I also realized that everything was different now.
We couldn’t lose track of our emotions, certainly, but we couldn’t give in to them the way we used to. Maybe Rocky and JoJo would need this information someday. Dr. Chatterjee certainly needed it now.
I finished telling him about the scene at the water tower and said, “Like those ants in that video you showed us. With the parasite?”
He took off his glasses and polished the lenses on his rumpled button-down shirt, though they did not look in need of polishing. “Ophiocordyceps unilateralis,” he said quietly. “The pieces are starting to fit together.”
“How?” Patrick said.
“Those adults out there”—Chatterjee pointed a trembling finger through the doorway of the nearest classroom to the windows and beyond—“have been infected.” He shook the detector, the words blinking out at us again: UNIDENTIFIED PARTICULATE. “This parasite attacked their white matter.”
“So why didn’t it attack ours?” Alex asked.
“You’re teenagers,” he said. “You have less.”
Patrick drew back his head. “We do?”
“Of course. Kids have a lesser-developed frontal cortex.”
“Rub it in,” Alex said.
“Look,” Chatterjee said. His hands shaped the air as they did when he was in teacher mode. He seemed to forget that one of them was gripping a clawhammer. “Every year from childhood on, white matter wraps around more and more of the nerve cells of the brain—that process is called myelination.”
“What is white matter?” Rocky asked.
As the sun inched up, squares of light from the windows stretched across the classroom floor opposite us. Some of the male Hosts had drawn closer to the school, spiraling their way around the front parking lot. One man in a scuffed denim jacket drew closer to the fence, his shoulder rat-a-tat-tatting along the chain-link, the sound sending electricity up my spine. Dr. Chatterjee took Rocky by the arm, drawing him out of sight past the doorway, the rest of us following. Sensing that something was wrong, Cassius leaned into my leg, his black-mask face pointed up, no doubt reading the stress coming off me.
“White matter transmits information from different parts of the body back to the cerebral cortex,” Chatterjee said, the hammer wagging by his face. “Which helps with executive function—decision making, attention, planning, motivation. Think of the myelination of axons as creating information pathways, connections that allow communication between all the parts of the brain. That’s what maturity is, really. Teenagers grow more white matter every year. But the last part of the brain to be myelinated is the frontal lobe.”
“So you’re basically saying we’re all stupid,” Alex said.
Chatterjee shook his head. “I’m saying that part of being a kid, a teenager, is that you literally don’t have the capacity yet to think fully about the consequences of your actions.”
Alex cut in: “Where have I heard that before?”
Patrick had leaned back around the doorjamb to spy on the Hosts outside. Chatterjee yanked him back, as if proving his point, while barely slowing down. “That’s why teenagers can be impulsive, angry, lovesick, higher in risk taking—”
“Well,” Patrick said. “We’ll need risk taking now.”
“That’s absolutely true. But if what Chance is saying is correct, then this airborne parasite invades its host and gains control by spreading through the white matter, seizing control of the frontal cortex.” He waved the clawhammer in a circle. “From there it takes over the brain and the nervous system, manipulating the host like a puppet. It can run the human body as if it’s a machine, operating the muscles without regard for pain or injury.”
I thought about Uncle Jim’s death shudder. All those men we’d seen out there, walking their mindless spirals. Coach Hanson scrabbling forward to get us, not even caring about the bone sticking out of her leg.