“That’s easy for you to say, Tarzan,” Brownley moaned, gasping for air. “You’re only twenty-four. I’m forty-nine—or I was before I started up that wall. Now I’m sixty-nine.”

“Let’s go, old man,” Eric said with a grin. He moved quickly in a low crouch to a dark shape that was emitting a low hum.

Brownley lurched to his feet, muttering to himself, “Which means I’ll be eighty-nine when I get down.”

“Here’s one,” Eric said, tapping on the air-conditioning unit. Then he pointed. “There’s the other.”

Brownley could manage only a nod as he collapsed next to Eric, who was opening the sack and pulling out the two plastic bottles.

“Will the air conditioning send this stuff all the way through the building?”

“Oh, yes,” Brownley said. “These will do just fine.” He uncorked the first bottle. “Avert your head and cover your face, please,” he said, following his own command. “It would be a shame if we took a whiff of this and ended up sleeping peacefully on the roof.”

“Are you sure this stuff will work?” Eric put his arm across his face as Brownley poured in the liquid.

“Of course. As I told you before, it’s colorless, odorless, brings unconsciousness in less than thirty seconds, and the person wakes up in about an hour with no side effects other than a slightly fuzzy head. One of the chemical companies I consulted for before Termination developed it for the CIA and other intelligence agencies.”

“And you’re sure it’ll be gone by the time we’re ready to go in?”

Brownley shook his head. “You make me feel a little better about being afraid to climb up that wall.”

“Well, this stuff makes me nervous.”

“It breeds a healthy respect in me too,” Brownley agreed. As they moved across the roof to the second air conditioning unit, he continued. “But, yes, it’ll be gone by the time we go in. It gassifies on contact with air and dissipates very quickly.” He uncorked the second bottle and, averting his head, poured it slowly into the whirling fans. “All right. That’s it.”

“Good, let’s get out of here.”

“Any other way down besides the back elevator?”

“Sure, I’ll call you a helicopter.”

“Your empathy and understanding are really touching,” Brownley sighed. “Why don’t you just throw me off?”

They had reached the edge of the roof, and Eric handed him the rope. “That’s my second option,” he growled, “so get going.”