Strangers

held it so he and Jack and Pollard could see the four-inch-square video display, which was dark. Three retractable probes were slotted in the SLICKS, and Jack withdrew the first of these from its niche: It looked like a copper-tipped steel thermometer on a two-foot wire umbilical. Jack looked closely at the partially exposed guts of the electronic lock and carefully inserted the slender probe between the first two buttons, touching it to the contact point at the base of the button marked '1'. The display screen remained dark. He moved the probe to button number 2, then 3. Nothing. But when he touched number 4, a pale green word - CURRENT - appeared on the screen, plus numbers that measured trace-electricity in the contact.
        This meant that the middle number of the three-digit lock-code was 4. After loading sacks of money and checks into the cargo-hold at the last stop on the route, the driver had pushed 4 to activate the lock. The contact point of that button would remain closed until the entire code was punched in, thereby unlocking the door.
        With three unknown numbers, the possible combinations had been one thousand. But now that they needed to find only the first and last numbers, the search was reduced to one hundred combinations.
        Ignoring the howling wind, Jack withdrew another instrument from the SLICKS. This was also on a two-foot cord but resembled a watercolor brush though with a single bristle. The bristle glowed with light and was thicker than a sixty-pound fishing line, stiff yet flexible. Jack inserted it into a crack at the base of the 1 button on the lock keyboard, glanced at the computer video display, but was not rewarded, He moved the bristle-probe from number to number. The display screen blinked, then showed a partial diagram of a circuit board.
        The bristle that he had thrust inside the mechanism was actually the end filament of an optical laser, a more sophisticated cousin of the similar device which, in supermarket cash registers, read the bar codes on grocery items. The SLICKS was not programmed to read bar codes but to recognize circuitry patterns and render models of them on the display screen. The screen would register nothing whatsoever until the bristle-probe was aimed directly at a circuit or portion thereof, but then it would faithfully reproduce the hidden pattern that it saw.
        Jack had to move the probe three times, insert it into the lock mechanism at three different points, before the computer was able to piece together a picture of the entire circuitry from partial views. The diagram glowed in bright green lines and symbols on the miniature video display. After three seconds of consideration, the computer drew boxes around two small portions of the diagram to indicate those points at which a tap could easily be applied to the circuitry. Then it superimposed an image of the ten-digit keyboard over the diagram, to show where those two weak points were in relation to that portion of the lock mechanism that was visible to Jack.
        "There's a good tap-in spot below the number four button," Jack said.
        "You need me to drill?" Pollard asked.
        "I don't think so."
        Jack returned the optical probe to its slot and withdrew a third slender instrument with a spongy mesh tip of some material he could not identify, which the designer of SLICKS had labeled the "tap-wand." He inserted it through the tiny gap in the lock mechanism at the base of the 4 button, slowly moved it up and down, left and right, until the computer beeped and flashed INTERVENTION on the miniature video display.
        While Jack held the tap-wand in place and Chad Zepp held the SLICKS upright, Pollard used the computer's small programming board to quickly type instructions. INTERVENTION disappeared, and onto the screen came other words: SYSTEM CONTROL ESTABLISHED. The computer could now feed commands directly to the microchip that processed the lock codes and that directed the sliding steel bolts to either close or open.
        Pollard hit two more keys, and the SLICKS began to send sequences of three numbers to the microchip, one combination every six-hundredths of a second, all of which used the already known 4 as the middle digit of the code. SLICKS hit the right code - 545 - in only nine seconds.
        With four simultaneous thumps, the lock bolts retracted as one.
        Jack returned the tap-wand to its niche, switched off the computer.