“Charles, I just can’t b u y a woman doing this,” said Riker.

“Because the victims are children? Let’s say Mr. Linden was the first adult victim. A child can be coerced by guile and easily managed with minimum strength. A full-grown man is a whole new problem-for a woman. Hence the careful planning of Linden’s murder in contrast to the more risky behaviors-transporting the body and laying it out in such a public place. I see a cockiness that comes from experience and confidence.”

Kronewald seemed skeptical. “You think the next victim will be another adult?”

“Since Mr. Linden was the father of a missing child-probably a murdered child-the killer may have changed his focus to the parents.”

“And that ties back to Dr. Magritte’s caravan,” said Riker.

The Chicago detective pretended not to hear this, perhaps because the caravan had already traveled into the next state, a moveable feast for a serial killer, and Kronewald was being left behind. He resumed his chore of marking out gravesites between Chicago and the southwest border.

“I have one more disagreement with your department psychologist.” Charles hardly needed to consult his own map, the one Riker had marked for him in red to show all the different names for the same old chopped-up highway and all the towns it passed through. “Linden’s killer wasn’t out for thrills. He just needed another body to decorate his road.”

“His… road,” said Kronewald. The detective lifted his pencil from the map.

Riker leaned over to see what had been drawn. “Oh, shit. Five graves on that route, and you’re not even done yet, are you? Don’t e ven think about spinning me a lie. How many bodies so far?”

Kronewald looked down at his map. “I swear there’s only five confirmed gravesites we can link to the feds’team of body snatchers.” He looked down at his map again. Reluctantly, his pencil moved on to draw more X’s. And now there were ten. “These three here.” He tapped the map with one finger. “These are places where an FBI helicopter was reported landing. Evidence of digging, but no confirmation on whether or not the feds stole a body.”

“And the last two?” Riker leaned closer. “Come on! Give! ”

“Fifteen years ago, a pack of kids found a grave here.” Kronewald tapped the map location with his pencil. “They thought a pile of rocks just looked too neat-like somebody was hiding something. So they started digging.” His pencil moved to another gravesite. “And this one was found when a phone pole was relocated. That was about ten years ago.”

Riker closed his eyes in the manner of a man who has seen enough for one day. “I’ll ask once. I know about the lines and the circle carved on Linden’s face. And I know you were never gonna share that, okay? So don’t bullshit me. Just tell me this. Do the lines and the circle look like a number? A hundred and one? A hundred and ten?”

Before the other detective could answer, Charles said, “My guess would be a hundred and one killings. It works nicely with a sudden drastic change in victim profiles-children to adults. Am I correct?“

Kronewald nodded.

“Well, then,” said Charles. “It appears that your department psychologist was right about the territorial aspect. Unfortunately, this killer’s t e rri-tory ranges for another two thousand miles beyond Illinois. He’s fixated on Route 66.”

Eyes wide open now, Riker leaned close to Kronewald, as if to whisper in the man’s e ar, and then he yelled, “But you already knew that!”

Mallory had traveled thirty miles into the state of Missouri to arrive in time for the last tour of the caverns, but it had been disappointing so far. Trailing behind a small group of German tourists on a trek of more than three hundred feet below ground, she listened to the tour guide’s spiel on points of interest: three species of bats never seen and a river of blind cave fish that were also unseen because they shied away from the light-even though they were blind. Now and then, the guide would pause to turn on a switch so lights could dramatically illuminate stalactites and stalagmites.

Mallory endured all of this.

If she could only believe in the man who had written the letters, the best was yet to come, and he had promised, “-the payoff will be Miss Smith.”

Onward and upward they walked single-file on a gentle incline to the finale, touted as the world’s largest cave formation. “Seventy feet high,” said the guide, “and sixty feet wide. Millions of years old.”

Following the Germans, Mallory climbed some fifty-odd steps to arrive in another cave. This one was outfitted with rows of chairs facing into the dark. When the small audience was seated, the guide turned on the lights to stun them with a formation of stalactites that draped in the shape of an immense theater curtain. The rock bed below it resembled a stage with the hollow of an alcove where a narrator might stand.

Now she understood the poetry that had accompanied this landmark in the letters, lines from Rilke: “And you wait, are awaiting the one thing / that will infinitely increase your life / the powerful, the uncommon, the awakening of stones.” Mallory stared at this fantastic formation like any other theatergoer who had every right to expect the ancient curtain to part, the rock to open wide. Anticipation alone was exquisite-almost magic.

The guide was reciting a history that involved a large-chested diva of the nineteen fifties, the late Kate Smith, and now he had Mallory’s attention again, for Miss Smith was the promised payoff.

“On with the show,” said the guide as he pressed a button on a console. A woman’s booming voice sang, “God bless America-” at a startling volume. The lights flashed red, white and blue, and, for the finale, a gigantic American flag was projected onto the natural wonder of the stone curtain.

The German tourists were tactfully, quietly shocked by this marriage of staggering beauty and kitsch. The guide was crestfallen, perhaps expecting applause for the dead diva, the flag and the disco lights. Those who knew Mallory and swore she had no sense of humor would never have looked to her as the source of the giggling. It bubbled up out of her mouth, and, unaccustomed to any spontaneous outburst of happiness, she was helpless to stop it. Her on/off switch for the giggles had been lost when her mother died. She laughed-she roared. The rest of the party, fearing hysteria, hovered around her but could do nothing with her.

Mallory recalled another line of the letter, the one that had lured her in here; and now she recognized it as the punch line to this joke on a grand scale: “The Midwest is a very scary place.”

The FBI rendezvous point was near another gravesite, and the special agent in charge could observe the diggers from the window of his room.

Dale Berman was a man of ordinary features and below average height, yet he knew that most of his associates would describe him as handsome in the way that professionally charming people can seem more attractive than they truly are-taller and wittier, too. For the past six months, he had joked about spending his retirement years writing a book on Route 66, a tourist guide on how to survive in these motels. Whether the accommo- dations were deluxe or as shabby as this one, he always slept on the side of the bed that was opposite the telephone, for near that phone-side pillow, the last ten thousand guests had planted their rear ends while calling home.

Special Agent Berman would soon be taking early retirement, and his wife, playful old girl, was counting off the calendar dates by carving wide notches into their front door so he could not fail to have his paperwork in order when the great day came.

He squinted as he leaned closer to the window, watching his team of gravediggers racing the light of day, brushing away the dirt and sifting it for clues to a skeleton’s identity. In response to a knock at his door, he called out, “It’s open!” He turned to face his last appointment of the day. The man entering the room was the senior forensics technician from the Illinois digs. That sector of the investigation had always been a battleground.