He gestured toward the wooden crate on the bench. "Show me what you've built.
I'll explain to Mrs. Larkin why it's dangerous, and then we can all go back to our lives."
Boon looked at him for a moment, then said evenly, "All right, but fair is fair. We look at both my braces and yours side by side on the same bench."
He laid the two sets of braces parallel under the shop light, one side gleaming, stamped with three curved waves, one side bare metal, still carrying the marks of the file.
"Mrs. Larkin," Boon said, looking not at Crane but straight at the mother.
"You don't have to trust me. You don't have to understand the engineering.
I'm only asking for three minutes of your time, and you'll see it for yourself with your own two hands."
He handed her a luggage scale with a hook. "First thing, weigh them yourself.
Both sets."
Genevieve hesitated, then hooked the scale onto the Vitamotion braces. The needle read nearly 12 pounds.
She hooked it onto the bare aluminum braces. Seven.
"Your daughter has carried that difference on two paralyzed legs every step, every day, for years," Boon said. "Second thing."
He handed her both braces and pointed at the knee joints. "Bend each joint with your own hands."
Genevieve flexed the Vitamotion joint. It dragged through a single dead plane, and when she bent it quickly, it let out that exact click she had heard from her daughter's legs a thousand times without ever letting herself notice.
Her face changed. She flexed Boon's joint.
It turned smoothly, adjusting itself to the angle of her hand with a suppleness that was almost alive. "Tactile impressions are not clinical data," Crane cut in, his voice beginning to lose its warmth.
"Third thing," Boon continued as if he hadn't heard. He opened the leather notebook to the pages dense with measurements.
"This is the pivot axis of the human knee, taken from anatomy references anyone can buy at a bookstore." He laid a machinist's protractor against the joint of the Vitamotion brace, the kind of tool every mechanic owns.
"Doctor, read the number yourself." Crane didn't need to read it.
He knew that number. He had known it for a very long time.
And in that exact moment of hesitation, half a second, no more, Genevieve Larkin saw it. The woman who had sat across a thousand negotiating tables, who had made her living reading opponents' faces, saw that half second.
"Nathaniel," she said slowly. "Read the number."
"Genevieve, manufacturing tolerance deviations are perfectly normal. Piper has complained of pain in her right knee since she was 12 years old."
Mrs. Larkin's voice dropped lower with every word and grew more frightening with every word.