He craned his neck around as he ran, but could see nothing. The only sound he had heard was that of the projectile slamming into the tree: there was no sound of the detonation within a rifle chamber. Sound-suppression gear was quite possibly in use. But even with a silenced rifle, a supersonic round produced a noise as it emerged from the muzzle—not necessarily a conspicuous one, but a noise all the same, like the crack of a whip. Janson knew that noise well. The fact that he had not heard it suggested something else: it was another long-distance shot. If the gunman were a hundred yards away, the noise would be lost amid the baffling provided by the tree leaves and the park’s ambient sounds. Conclusion: an extremely skilled marksman was in pursuit.

Or a team of them.

Where was safety? It was impossible to say. Worms of apprehension writhed in his belly.

Dirt kicked up a couple of feet from him. Another near miss. The shot had been taken from a very great distance, and the subject had been in motion: for a shot to have come within ten yards of him would have represented impressive technique. Yet this shot had come within a couple of feet. It was astounding. And terrifying.

Keep moving: confronted with unseen pursuers, it was the one thing he could do to make himself a more difficult target. But movement itself was not sufficient. He had to keep his speed irregular, for otherwise a trained sniper could calculate the “lead” in his sighting. It was a straightforward exercise to fire at a target who was moving at a fixed speed in a fixed direction: taking into account distance and target speed, you measured out a few degrees to the left of the figure in your scope, firing at where the target would be when the bullet arrived, not where it had been when the bullet was fired.

Then there was the crucial matter of the sniper grid. Lateral movement—transverse velocity—was one thing. But movement that took the pedestrian target toward or away from the sniper was of almost negligible importance: it would not prevent the bullet from reaching its target.

Janson had not determined how many marksmen were in position, or where those positions were. Because he did not know the grid, he did not know which movements were transverse, which not. The rules of flanking and enfilading would stipulate an axial array; marksmen as accomplished as these would be conscious of the peril of bullet “overtravel,” which could be fatal to a member of the team or a bystander.

The snipers—where were they? The last two shots came from the southwest, where he could see nothing but, a few hundred yards away, a stand of oak trees.