 How is Lane able to hover over the buildings?
Raging , Trooper Lane hovered three thousand feet above Tammany Square. The humming paragrav-paks embedded beneath his shoulder blades held him motionless above Newyork's three administrative towers. They don't teach them about their own city, that they'll be fighting for. Two black paragrav-boats whirred along the translucent underside of Newyork's anti-missile force-shield, the Shell. Lane somersaulted. Cybrain had taken charge of his motor nerves. He began to plummet down, picking up speed. A predatory excitement rippled through him as he sailed down through the air. Lane dropped lightly to the floor, inside the room, in battle-crouch. "Lashing police with his vibray," said the announcer, "Lane broke through the cordon surrounding Manhattan Armory. Tammany Hall has warned that this man is extremely dangerous. Citizens are cautioned to keep clear of him. A built-in electronic brain controls his reflexes—" "At ease with that jazz," said Lane, and a sheathed finger snapped out. The two police boats were hovering above the towers. Lane's mailed hand snapped open a pouch at his belt. The force-bomb "exploded"—swelled or inflated, really, but with the speed of a blast. A section of the energy globe bellied out from above. It shaded the view from his window and re-entered the tower wall just below. "Force-screen. Sure, I've heard of it—you gotta go by spaceship. Gerri Kin said, "That's what the force-domes did. But also the road to the return to city-states. The rounded black hulls of the two police paragrav-boats were nosing toward the force-screen. A loudspeaker shouted into the room: "Come out of there, Lane, or we'll blast you out." Mars is millions of miles away, and you're right across the Square from the Mayor's suite." The police boats backed away slowly, then shot straight up, out of the line of vision. Far below, the long, gleaming barrel of a blaster cannon caught the dim light filtering down through Newyork's Shell. The cannon trundled into the Square on its olive-drab, box-shaped caterpillar mounting and took up a position equidistant from the bases of the three towers. Lane stared down to see a large crowd gathering in Tammany Square. There were white dot faces on the balcony that Gerri Kin had pointed out as the Mayor's suite. "Lane is holding the Martian Ambassador, Gerri Kin, hostage.
 He has anti-gravity devices implanted in his body.
 He has anti-gravity boots.  He is in a helicopter.  He has a jet pack.  He has anti-gravity devices implanted in his body.