“Snow’s weak,” he said, “but he’ll be back. He needs your son now more than ever.”

Mike felt every part of his body fall heavy and still, as if his insides had been replaced with a poured plaster cast of themselves. “With the ax still in him?”

Walker’s expression hadn’t changed. “Let me go back and try to find him. At least I can create some kind of diversion so you and your family can run for the exit.”

Mike stopped and thought about it. “There might be another way.”

“Even weakened, you won’t be able to kill what’s inside of him.”

“We’ll see.”

Walker looked at him. “What are you thinking?”

“I’ll need your help,” Mike said.

They went back up, heading through the door to MRI. Mike crossed the suite to the outer console, past the desk. The red button outside the scan room was confined in a yellow square and shielded by a hinged piece of thick plastic. The sign beneath the button said:

EMERGENCY SWITCH

Operation of this switch will deenergize the magnet.

WARNING!

Energizing the magnet is a long and very costly process.

Mike read these words over, as he had a hundred times before, then looked back at Walker, Sarah, and Eli. The four of them were right in front of the outer console, less than twenty feet from where the man with the serpent tattoo had been handcuffed in his stretcher the first time he had laid eyes on him, six hours and a million years ago.

“Come over here,” Mike said. “We’ll need to stay down.”

“Mike?” Sarah blinked at him. “What are you doing?”

But Dr. Walker was nodding. “I think I know what to do,” he said. “It’s all right.”

“Listen—”

“You have to trust me. I can do what’s required. I still have that ability.” Walker’s eyes darted to the red button on the wall. Then he seemed not to notice the rest of them at all. “You do, too, don’t you?” he asked without turning around.

Without waiting for Mike’s answer, the doctor walked to the doorway of the scan room, leaving the door open behind him. For a moment Mike saw Walker through the glass, standing in front of the magnet, his scorched and bloody lab coat hanging off him like the last remaining actor at the end of some modern adaptation of a Shakespearean tragedy.

Sarah’s voice whispered, “Mike, what’s he…?”

“Shh.” He reached down and found the shape of her hand. “Crawl down here under the table with me.” He helped her and Eli out of the chair, guiding them along the floor beneath the table until his wife and child were braced against the wall. “Stay here. Whatever happens, don’t move and don’t make a sound.”