But Super Senses told Lynn there was a metal foreign object 3.7 centimeters beneath the scar, about nine millimeters in diameter.
Its vibration frequency was completely different from that of the surrounding tissue—it had the faint, high-frequency resonance unique to Vibranium.
"When did you get hit?" Lynn asked.
"Two weeks ago," Claire answered for Luke.
She spoke quickly, as if she had prepared this explanation in advance.
"Someone in the Harlem District got hold of a batch of special bullets. Luke was shot while stopping a shooting, and the bullet pierced his skin. It was the first time he'd ever been seriously injured by a bullet."
"But the problem is, his skin heals too quickly." Claire's voice held unmistakable frustration.
"Before we could get the bullet out, the wound closed up. Now it's sealed inside his body, and the skin on the outside is so hard that—well, nothing can cut through it."
"What have you tried?"
"Drills. Chainsaws. And sulfuric acid." Claire rattled them off in one breath.
"The drill just slipped off without leaving a mark. The chainsaw managed to generate a little heat on the surface of his skin, but it cut zero millimeters deep. As for the sulfuric acid—I used industrial-grade concentrated acid and left it on his skin for forty minutes. It only softened the outer layer by less than 0.1 millimeters."
"And the sulfuric acid hurt like hell," Luke added.
His voice was deep and resonant, as if it rolled up from his chest.
"I'm not afraid of pain, but that kind of pain is pointless. The acid can't get in, and the bullet can't get out."
Lynn didn't answer right away.
He held his hand above the scar on Luke's abdomen, gently pressing with his fingers.
Super Senses let him feel through the surface of the skin—he could sense the structure of Luke's skin.
It wasn't ordinary human skin.
Normal human skin had three layers: the epidermis, the dermis, and the subcutaneous tissue.
Luke's skin had those same three layers, but each was far denser and harder than normal.
The dermis in particular contained a protein structure Lynn had never seen before. It was arranged with extraordinary density, forming a multilayered web of crisscrossing fibers.
The deep-scan mode of All-Things Diagnosis provided even more precise data: the natural resonant frequency of this protein network was 39.14 kilohertz.
Natural frequency.
Every material had a natural frequency.
When an external vibration matched a material's natural frequency, resonance occurred.
In a resonant state, the material's internal structure temporarily loosened.
Luke's skin wasn't impenetrable—no one had found the right "key."
"I need an ultrasonic device," Lynn said. "High-frequency. It needs to adjust to at least two decimal places. Military-grade would be best."
Claire raised an eyebrow. "Ultrasound?"
"Yes."
"You're going to cut open his skin with ultrasound?"
"Not cut it. Soften it."
All three of them looked at him.
Matt couldn't see, but his face was turned toward Lynn as he listened to Lynn's heartbeat and breathing, using the data to judge whether he was bluffing.
"Are you sure?" Luke asked.
"I need the device before I can be sure," Lynn said. "But it should work in theory. The problem is, equipment with that kind of capability isn't available through ordinary channels."
He looked toward the door.
Frank had said he'd be back late when he went out "on patrol" that evening.
But he'd left Lynn a way to contact him: a disposable number used only to receive text messages.
Lynn sent a message: "I need a military-grade ultrasonic generator, frequency range 30–50 kHz, precision 0.01 kHz. Within two hours. Can you get one?"
Thirty seconds later, a reply came: "One hour and forty minutes. I'll leave it at your back door."
"The equipment's on its way," Lynn told Luke. "Get some rest. We'll operate in two hours."
1:37 a.m.
Lynn carried the military equipment case Frank had left on the back-door steps into the VIP Operating Room.
He opened it.
Inside was a military-grade ultrasonic generator, a USG-M7 series model used by U.S. military medical units.
It would normally cost more than thirty thousand dollars. Lynn didn't ask how Frank had managed to get one in an hour and a half.
He asked only, "Will it work?"
Frank replied with one word: "Yes."
Lynn spent forty minutes modifying the device.
Batman's mechanical engineering knowledge, accessed through Super Intelligence, proved invaluable—
He recalibrated the circuit parameters of the frequency-generation module, increasing the output frequency precision from the kilohertz level to four decimal places.
Then he handcrafted a focusing probe from a stainless-steel tube from the clinic and a piezoelectric crystal salvaged from an old piece of equipment.
By the time he finished, it was 2:20 a.m.
Luke had been waiting in the examination room for nearly three hours.
Claire stayed with him.
Matt sat in the waiting area outside, leaning against the wall and pretending to rest, but his Super Senses kept monitoring what was happening inside.
"It's ready." Lynn opened the door to the VIP Operating Room. "Only you come in. Everyone else waits outside."
Claire opened her mouth to say something.
"He doesn't need an assistant for this operation," Lynn said, looking at her. "And you might see things in there that you'd rather not see."
There was a lot to unpack in that statement.
Claire hesitated, but in the end, she didn't insist.
Luke walked into the operating room.
His size made the room feel considerably more cramped.
When he lay down on the operating table, its metal frame gave an unhappy creak.
"You sure this table can hold me?"
"It can. I reinforced it myself."
Lynn secured the modified ultrasonic probe to an adjustable stand and pointed it at the scarred area on Luke's abdomen.
"What I'm about to do might be something you've never seen before," Lynn said as he adjusted the equipment.
"I'll use ultrasound to create localized resonance on the surface of your skin. The resonance will temporarily soften it—the window will be short, probably only thirty or forty seconds. During that window, I'll cut through the skin, find the bullet, and take it out."
Luke stared at the ceiling. "How do you know ultrasound can soften my skin?"
"Because every material has a natural frequency. Your skin may be hard, but ultimately it's still made of protein molecules. Proteins have their own molecular vibration patterns. Applying a matching frequency can temporarily disrupt the cross-linked structures between the molecules."
"You study physics on top of being a doctor?"
"I learn things quickly."
Lynn switched on the ultrasonic generator.
A low hum filled the operating room.
He began adjusting the frequency.
Before you continue