Through a set of binoculars painted with urban camouflage, he scanned the windows of the building across the street. One by one he gazed at them, looking for an elusive sign of the slightest movement. He had been here on the seventh floor of an abandoned, unlighted office building for days, without sleep, always watching, and he knew that the one he was looking for had been here longer. He could hear the wind outside through the windowpanes. Suddenly, he felt footsteps far below. Was someone approaching? He told himself not to panic, to concentrate on the goal, but still, he felt highly uncomfortable. If they found him here, it would be all over. His left hand slowly moved toward his belt holster. Suddenly, he spotted something in an eighth-floor window across the street. A flash of movement! Instinctively he reached for something on his back, but something told him that he could not. There had to be no trace. A misplaced burst of light and sound was all it took to blow his cover. So he waited a while longer,