"This way, Colonel." Herz gestured back to the front awning of the tent. "Let me show you what we found."

Forensics had already finished with the big top before Herz beckoned Smith past the incident tape and into the open space within. Smith glanced around curiously. Like any big top, its roof was held up by a pair of huge posts. But the resemblance stopped at that point; there were no seats, no trapezes or safety nets, and nothing in this particular ring could be described as a laughing matter.

"It's a regular headquarters setup, we think," Herz commented as she walked towards a row of tables at one side of the huge tent. "Look." The tables showed every sign of having been abandoned in a hurry: folding chairs tipped over, equipment crates lying on their sides. One of the tables was covered completely by a large relief map, various implements strewn across it-notepads, pens, protractors, and folded pieces of card.

"Pay dirt," breathed Smith. He paused momentarily. "Has it been checked out?"

"Everything's been photographed in situ. I think they even dusted for fingerprints, just in case."

"Gotcha." Smith leaned over the map. It didn't take much to recognize the foothills, and the river valley forking downstream. But there was something odd about the map. He frowned. "Concord should be here, shouldn't it?"

Herz followed the direction of his finger. "I guess so."

"Hmm. Look." The moving finger trailed south. A much smaller clump of buildings perched beside the river, surrounded by a sharply incised wall. "This is printed. It's even got grid coordinates. Betcha they bought the map data from someone over here, in our world, then added their own survey points. Saves time, assuming the geography's the same, and I guess they would know about any major features like landslides."

Herz shook her head. "You mean this is a map of, of fairyland."

"It's not fairyland," Smith said sharply. "It's real enough that they can make a map of it like this, and plan…"

He paused, then peered back at the map. Hunting upstream of the small town, at the fork in the river, he found what he was looking for. "Go get one of our maps. I want to confirm that this is where we are," he said, moving one of the cardboard markers to sit atop the heptagonal feature he'd noticed. "They were here for a reason, and I want to know what they were doing that took nearly two hundred of the bastards."

He straightened up and looked around. There were more tables dotted around, and a stack of empty kit bags, but the center of the tent was dominated by a two-story-high aluminum scaffold with ramps and ladders leading up to platforms on both upper floors. Surveyor's posts and reflector disks fastened to the uprights, and a pair of theodolites at opposite sides of the tent, made it clear that whoever had built the scaffold had taken pains over its exact location. Smith frowned, thoughtful. Nearly two hundred of them and they vanished into thin air in less than three minutes. How did they avoid falling over each other? A precision operation, like paratroops jumping in quick succession from the back of a plane. And why did they do it out in public, risking detection? It had to be something to do with this location, and whatever it was collocated with in the other time line.

Herz was muttering into a walkie-talkie. "I need geographic input. Is Amanda-yes, I'll hold, over."

Smith walked partway round the scaffold. A faint memory began to surface, grade school on an Air Force base somewhere in Germany: knights in armor, huge creaking wooden contraptions grinding their way across a field of battle towards a walled castle. The whole mediaeval thing. It's a siege tower. A siege tower without wheels, because you could build it in a parallel universe, butting right up against wherever you were going to go in. A siege tower without armor, and made of aluminum scaffolding components because they were cheap and easier to use than logs.

Voices pulled him back to the present. He glanced round, annoyed, then frowned. It was his political supervisor, Dr. James, with the cadaverous face and the connections to the current occupant of Number One Observatory Circle, plotting and scheming inside the beltway. A couple of flunkies-administrative assistants, pasty-skinned managerial types from Crypto city, even a discreet Secret Service bodyguard doing the men-in-black thing-followed him. "Ah, Eric! Excellent, Martin, you can stop trying to reach him now. What's your analysis?"

Smith took a deep breath, held it for a moment. The smells of crushed grass and gun oil and desperate men filled his nostrils. "It's a siege tower. They weren't running away from us, they were breaking into something." He gestured at the theodolites and the scaffolding. "That's positioned with extreme care. I think it's a siege tower-they had a target in their own world and this took them to a precise location. The map"-Herz was waving at him-"excuse me." He walked over to the table. "Yes?"

"You were right," she said. "We're here." Her finger stabbed at the heptagonal structure. "This thing is about five hundred feet across, look, concentric rings-does that remind you of anything?"

Smith nodded and turned to Dr. James. "If their map's telling the truth, that structure is some kind of fortification. And we already know from CLEANSWEEP that some kind of internal struggle was going down fourteen to sixteen days ago. We could do a lot worse than send a couple of scouts across in the next valley over." He cracked his knuckles, first the right hand then his left. "It's a shame we don't have anything that can touch them, because they're probably still there, in strength."

James grinned like a skull. "Well, I have an update for you. Let's take a walk."

BEGIN TELEPHONE TRANSCRIPT:

(A telephone buzzes for attention.)

"Hello?"

"Ah, is that the Lee residence?"

(Pause.) "Who is this?"

"I'd like to speak to James Lee, please. It is dringenurgent."

(Pause.) "Please wait."

(Two minutes later.)

"Hello? Hello?"

"Who is this? Is-James? James, is that you?"

"Ah, yes- Who, urn-"

"Poul, Poul yen Wu. You may remember me, from my cousin Raph's wedding to Kara ven-"

"Ah, yes! I remember now! Yes, indeed. How good to hear from you. But surely this isn't just a social call?"

"I wish it were. Unfortunately a somewhat delicate situation has arisen at short notice, and I hoped you might be able to advise me on how it might be resolved without undue difficulty."

(Pause.) "Ah. I see, I think." (Pause.) "Would this situation have anything to do with the events at the Thorold palace earlier this month?"

"Mm… in a manner of speaking, yes. It's a delicate matter, as I said, and we're anxious to resolve it without violating the terms of the settlement between our families, but it's quite urgent and it appears to be becoming time-critical."

"Hmm. Can you be more specific? I think I can safely say that we would also like to remain within the conditions of the truce, but I cannot commit to anything without my elders' approval, and I am quite anxious to know what I shall be putting before them."

(Pause.) "We would like to arrange for the safe passage of a substantial group of our people, from a location near Irongate-near Wergatsfurt-across a distance of some three miles, on foot, at night."

"Passage. You mean, from Wergatsfurt, in Gruinmarkt, to somewhere about three miles away, also in Gruinmarkt, but through our world, I take it?"

"Precisely." (Pause.) "In addition, the group is armed. Not civilian."

(Long pause.) "You're asking us to give safe passage to a small army."

(Hastily.) "Only for about three hours, at night! And there are only two hundred and eighteen of them. Eleven walking wounded, six stretcher cases. We don't want to attract attention-we want to keep it out of sight of the Polis, and everybody else. Can you-is it possible-to arrange this? I can supply details of the end-points of the sortie, and precise numbers-but what we would like, if it is possible, is not simply a dispensation within our agreement but active help. If you can organize covered trucks, and secure the destination, for example…"