They reached the first-aid tent just as a marshal sounded two short notes on a horn. The children’s beginner races were about to start. On the opposite side of the lot, Grant was slipping a dark cover over the rear of Leo’s cart.

Caleb took the nurse aside, told her Odessa was limping, and turned his attention to Iris’s photographs. The original design had a wide rear axle, with the brake centered on a solid crossbar. The replacement assembly was narrow and built around a moving yoke. More importantly, in a photograph from the previous week, Leo had mounted a small roll bar directly to the chassis. The replacement yoke now occupied the same area. Grant had shifted the bar’s attachment points farther back, onto a short support frame.

“The roll bar is connected to the moving carriage,” Caleb said.

Odessa looked at the photographs. “If he tips over, that bar will move with the wheels. It won’t protect him the way he thinks.”

Caleb felt cold despite the bright sun. He had been staring at the brakes. Leo was wearing a helmet; his head would be near the roll bar. He needed the boy away from the machine before it rolled an inch.

Across the lot, Silas held a microphone and thanked the sponsors for making the fastest Gravity Day in Bellwether history possible.

CHAPTER FIVE: THE DEMONSTRATION NOBODY WANTED

Caleb approached the officials’ tent with Odessa beside him and Iris’s photographs on his phone. Silas was about to announce the Lightning Class when Caleb asked for two minutes at the microphone. Silas refused before hearing why. Grant folded his arms and said the crowd had no interest in a technical quarrel.

“Then we’ll do it away from the crowd,” Caleb said. “Put a weight in the cart, bring it down the hill on a control line, and observe how it behaves at the patch.”

Grant’s expression changed. “That isn’t an approved test method.”

“What would be?”

“A professional road test.”

“Who’s driving it?” Odessa asked.

Grant glanced toward Leo. “The athlete.”

The absurdity hung between them. An untested machine could not be shown safe without putting the teenager in it; because the teenager was eager, the adults were treating eagerness as proof.

Caleb turned to the course marshal, a retired school custodian named Reuben Holt. Reuben had helped lay out Gravity Day for two decades. He had also taught Caleb that any volunteer could stop a run by raising a red flag if they believed something was unsafe. Silas had not changed that particular rule.

“Reuben, I am raising a safety objection,” Caleb said. “Will you stop the class until a neutral inspection?”

Reuben looked at Silas. Silas said the complaint came from a man upset about losing his place on the committee. Reuben shook his head.