Myrna laughed. “In a way. She gave me a tuque. We’d thought maybe she’d knitted it, but it was too old. And there was a tag sewn in it. MA, it said.”

“Ma,” said Gabri. “It belonged to her mother.”

“What did you call your mother?”

“Ma,” said Gabri. “Ma. Mama.”

There was silence, while Myrna nodded. “Mama. Not Ma. They were initials, like all the other hats. Madame Ouellet didn’t make that tuque for herself.”

“Well then, whose was it?” Ruth demanded.

“It belonged to Constance’s killer.”

*   *   *

Villeneuve rang the doorbell and his neighbor answered.

“Gaétan,” she said, “have you come to get the girls? They’re playing in the basement.”

“Non, merci, Celeste. I’m actually wondering if we could use your computer. The police took mine.”

Celeste glanced from Villeneuve to the large unshaven man with the bruise and cut on his cheek. She looked far from certain.

“Please,” said Villeneuve. “It’s important.”

Celeste relented, but watched Gamache closely as they hurried to the back of the house, and the laptop set up on the small desk in the breakfast room. Gamache wasted no time. He shoved the memory stick into the slot. It flashed open.

He clicked on the first file. Then the next. He made note of various words.

Permeable. Substandard. Collapse.

But one word made him stop. And stare.

Pier.

He clicked rapidly back. And back. And then he stopped and stood up so rapidly Celeste and Gaétan both jumped back.

“May I use your phone, please?”

Not waiting for an answer, he grabbed the receiver and began dialing.

“Isabelle, it’s not the tunnel. It’s the bridge. The Champlain Bridge. I think the explosives must be attached to the piers.”

“I’ve been trying to reach you, sir. They won’t close the tunnel. They don’t believe me. Or you. If they won’t close the tunnel, they sure as hell won’t close the bridge.”

“I’m emailing you the report,” he said, retaking his seat and pounding on the keys. “You’ll have the proof. Close that bridge, Isabelle. I don’t care if you have to lie across the lanes yourself. And get the bomb disposal unit out.”

“Yessir. Patron, there’s one other thing.”

By the tone of her voice, he knew. “Jean-Guy?”

“I can’t find him. He’s not in his office, he’s not at home. I’ve tried his cell phone. It’s shut off.”

“Thank you for trying,” he said. “Just get that bridge closed.”

Gamache thanked Celeste and Gaétan Villeneuve and made for the door.

“It’s the bridge?” Villeneuve asked him.

“Your wife found out about it,” said Gamache, outside now and walking rapidly to his car. “She tried to stop it.”

“And they killed her,” said Villeneuve, following Gamache.

Gamache stopped and faced the man. “Oui. She went to the bridge to get the final proof, to see for herself. She planned to take that proof, and this”—he held up the memory stick—“to the Christmas party, and pass it on to someone she thought she could trust.”

“They killed her,” Villeneuve repeated, trying to grasp the meaning behind the words.

“She didn’t fall from the bridge,” said Gamache. “She was killed underneath it when she went to look at the piers.” He got in his car. “Get your girls. Go to a hotel and take your neighbor and her family with you. Don’t use your credit card. Pay cash. Leave your cell phones at home. Stay there until this is over.”

“Why?”

“Because I emailed the files from your neighbor’s home and used her phone. They’ll know I know. And they’ll know you know too. They’ll be here soon. Go. Leave.”

Villeneuve blanched and backed away from the car, then he ran stumbling over the ice and snow, calling for his girls.

*   *   *

“Sir,” said Tessier, looking down at his messages. “I need to show you this.”

He handed his device over to Chief Superintendent Francoeur.

Gamache had returned to the Villeneuve house. And something had been emailed to Inspector Lacoste, from the neighbor’s computer.

When he saw what it was, Francoeur’s face hardened.

“Pick up Villeneuve and the neighbor,” he said quietly to Tessier. “And pick up Gamache and Lacoste. Clean this up.”