Gannon turned and bolted down the corridor and out the front door back outside.
He could see the taxiing 7500 through the thick tarmac-side fencing as he hopped in the Mercury and reversed it at speed down the terminal’s driveway and into its parking lot.
Back through the lot on its opposite side, there was a side wall of a hangar that fronted onto the tarmac.
Gannon bumped the Mercury up onto the sidewalk and turned the car in alongside it, almost touching its side.
He leaped out and lifted the M4 from the back seat. It was strapped to his back as he climbed up on the Mercury’s hood and then onto its roof.
There was a knot of electric and phone cables that came out of the ground up the side of the hangar to its roof and he quickly tugged at them, testing their weight.
Then he began hauling himself hand-over-hand up the side of the building as fast as he could.
The hangar’s roof was made of corrugated steel that rang hollowly under his heel when he swung his leg over on top of it.
Crouching low, he ran up the slope and at the top of the roof’s pitch, he dropped to one knee and looked through the carbine’s scope into the airport.
The 7500 was about two football fields away now, sideways to him, moving slowly as it turned off the taxiway right before one of the main runways.
Gannon lay down on his belly with a clatter. He laid the rifle between the corrugations, then thumbed the selector switch to single fire.
As he pressed in against the cheekpiece, he noticed the plane had come to a stop.
Gannon settled his right eye socket in comfortably against the gummy rubber edge of the scope.
Then he slipped his finger in above the flat trigger as he took a long, calming deep breath.