“It was a long time ago,” Stride said. “How can you be so sure?”

“You think I ever let Finn drive back then?” Rikke asked. “He never had a car. The only way he got anywhere was if I drove him. That night, we were both at home watching the fireworks.”

Stride leaned forward with his hands on his knees. “Did Finn know Laura?”

“Yes, we both did.”

“I understand Finn was in love with her.”

“Finn? Puppy dog love maybe. Nothing more. Laura was one of my favorite students—a sweet girl, very pretty, very quiet. She wanted to be a counselor for teenagers in dysfunctional families. She was passionate about it. I encouraged her to spend time with Finn, because I thought it would help them both. To her credit, she really devoted herself to Finn. I think she made a difference with him, and I’m sure he was grateful to her. To him, that was probably love.”

“What else can you tell me about Laura?”

“You should probably talk to Tish about her,” Rikke said. “The two of them were best friends for a while.”

“For a while?”

Rikke cocked her head. “Yes, they certainly weren’t friends at the end.”

“Oh?”

“God, no. They broke up very badly. Laura came to me in tears.”

“Did she say what happened?”

“She told me they had a fight.”

“What was the fight about?”

Rikke steepled her fingers together. She spoke slowly. “It was about a boy. Tish was insanely jealous. She demanded that Laura stop seeing him.”

“Who was it?”

“Laura didn’t tell me his name, but I always assumed it was the boy from that rich family in Duluth. The Stanhopes. I read in the papers after her death that Laura and Peter were seeing each other.”

Stride didn’t like where this was going. It made him wonder again about Tish’s motives in pursuing Peter Stanhope.

“Did Finn talk to you about Laura’s murder after it happened? Did he ever say he knew something about it?”

“Of course not. Like I told you, he wasn’t there.”

“I do need to talk to Finn,” Stride said, getting to his feet. “How do I reach him?”

Rikke waved her hand dismissively. “He comes and goes when he pleases. I’m not my brother’s keeper. Call the delivery company, and maybe they can help you find him somewhere on his route.”

Stride nodded. “I appreciate your time.”

Rikke didn’t reply.

“You know, I do remember something from your geometry class,” Stride added.

“Oh?”

“I think it was called the parallel postulate.”

Rikke shrugged. “If two lines cross a third and form less than two right angles, then eventually the two lines will meet if extended far enough. Why on earth do you find that so interesting?”

“It’s something I find in most of my investigations,” Stride told her. “Sooner or later, the lines always intersect.”

After Stride left, Rikke Mathisen stood at the living room window that looked out on the street. Holding aside the lace curtain, she watched Stride retreat into the dusky gloom and climb into his truck. His headlights burst on like two staring eyes, and then gravel scraped as he sped down the dirt road back to the highway, jolting across the railroad tracks. She watched until the red taillights disappeared and kept watching as night fell outside like a black cloud enveloping the house. Her orange tabby cat rubbed against her legs and mewed, but Rikke didn’t move. In the distance, coming from the northeast, a train screamed. Even at this distance, she felt its vibration under her feet. It didn’t matter how long she had lived here. She heard every train.