They all filed through the aisle and around to the far wall, where a small rectangular grille, about the size of a standard plastic flimsy, at ankle-height marked the return-air duct. "Go ahead and pull off the outer cover," Miles instructed the colonel. "It's the very top filter I'm interested in."

The whole crew of them ended up on their knees, watching over the colonel's shoulder. He pulled off the outer grille to reveal the sealed rectangle of fiber designed to catch dust, dirt, hairs, mold, spores, smoke particles, and the like; the tiny prokaryotes themselves, if freed from their sporelike cases, would have slipped right through this barrier and gone on, possibly, even to penetrate the electrolytic resin barrier behind it, only to be destroyed at the last when they reached the central flash-unit.

At Miles's nod the colonel gave way to Dr. Weddell, who sat cross-legged on the floor and earnestly saturated the air around the vent with his atomizer.

"So what's he doing?" the colonel whispered to Miles.

Miles suppressed the reply, We're spraying for traitors. Pesky vermin this time of year, don't you find? "Watch and see."

Weddell then pulled an ultraviolet hand-light from his box, and directed it at the filter. A pale red fluorescence slowly grew more brilliant as the black light played over the surface.

"There you are, my Lord Auditor," Weddell said. "The vector encapsulations were caught in the filter, all right."

"Just so." Miles scrambled to his feet. "That's our baseline, then. On to the next. You there"—he pointed to the forensics tech—"document, bag, label, and seal all that, and follow as quickly as you can."

The parade took their positions and followed him once more. This time he led them to the Department of Komarran Affairs, where Miles asked the disturbed General Allegre to join the procession. They all fetched up crowded into Captain Galeni's cubicle-sized office, fourth door down the Komarran analysts' corridor.

"Do you remember ever personally visiting Galeni in here in the last three months?" Miles asked Illyan.

"I'm sure I stopped in a few times. I came down here almost every week, to discuss items in his reports of particular interest."

As soon as the forensics tech arrived, out of breath, the colonel from Janitorial repeated his performance with the cubicle's return-air vent, identical to the one in Weapons Room IV. Weddell sprayed again, liberally. This time, Miles held his breath. The results of this test could force a major fork in his planned strategy. If Haroche had anticipated him—there had been two missing capsules, after all.

Weddell, on one hand and his knees, played his black light over the filter. "Huh." Miles's heart seemed to stop. "There's nothing here that I can see. Do you see anything?"

Miles inhaled, gratefully, as the other men bent to examine the filter also. It remained a slightly dirty and now-damp white.