avoid obstructions they don't see. An invisible man is an unseen obstruction. The three Marines had to duck, weave, and occasionally backstep to avoid people who were about to bump into them. They weren't successful one hundred percent of the time.
"Excuse me," a man in a flight suit said absentmindedly when MacIlargie found himself stuck between two people moving in opposite directions. The young Marine was able to avoid one but not both.
MacIlargie grunted something and spun away. The flight-suited man, with his hands swooping through the air, continued his conversation with his equally intent and swoop-handed companion. A few paces later the man in the flight suit realized he hadn't seen anybody where he'd bumped into someone and stopped to look back.
"What's the matter?" his companion asked.
"I bumped into somebody, but nobody's there."
"Sure there is." The companion pointed his chin at the person MacIlargie had managed to avoid when the flight suit bumped him.
"No, I saw her. It was a man's voice that said ‘No problem.’"
The companion looked at the doors lining the corridor. "Whoever it was must have gone into one of those offices."
"You think so?" Flight Suit wasn't sure there had been enough time for the man he bumped to make it to one of the doorways and through it before he looked back.
"Of course I'm sure. What else could it be?"
Flight Suit shrugged "I guess you're right. There's no such thing as an invisible man—and there aren't any Marines here." They resumed walking and returned to their conversation. Their hands began making flight patterns once more.
At last the Marines reached their next way point, a janitor's closet off a short side corridor, and ducked inside among the cleaning robots. Kerr shrunk the scale of his HUD floor plan, then rezoomed on the section that showed the route from there to the command center that was their objective.
"It should be tougher from here on," he said softly. "We're likely to start running into guards."
"The one in that first office was easy enough," Claypoole snorted, forgetting how much trouble he'd had subduing the sailor.
"From here in, they'll probably be more alert."
Claypoole stifled a remark about three Marines' swabbing up a headquarters full of squids, instead listening for his fire team leader's next orders.
Despite Kerr's concern, the only guards they encountered between the janitor's closet and their next way point were two petty officers flanking the ornate entrance of what was probably an admiral's office.
The guards, standing at parade rest, appeared to be more ceremonial than functional.
The next way station was their last. Kerr's HUD sensors showed no red dots nearby so they appeared to have a clear passage along the next two, short, corridors. He knew there was a guard station right beyond the range of his sensors. According to the intelligence reports, nobody could pass the guard station without being identified and cleared.
Kerr touched helmets with his men and said, "Here's what we're going to do..."
A minute later, halfway down the second corridor, a warning tone in their earpieces froze the Marines in their tracks. A sensor had picked up the emanations of a motion detector.
Kerr checked his HUD. The warning device was on the opposite side of the mouth of the next corridor on the right, the last corridor they had to follow. The motion detector was probably tied into a control panel at the guard station. They withdrew a few steps while they considered what to do about the motion detector. By that time they were close enough to the guard station for the HUD to show two dots representing the guards. The two dots were motionless, so either the motion detector hadn't picked up the Marines or the Marines weren't acting suspicious enough to draw the guards' attention—yet.
The Marines weren't carrying anything that could unobtrusively disable a motion detector. There was only one thing they could do.
"Plasma shields up," Kerr