Lightning

from the tablet. Then as an afterthought he hastily added: THE SECOND CANISTER OF    VEXXON. IT'S A WEAPON TOO.
    He searched the drawers of the lab bench for a glass beaker with a narrow top, but there were no such vessels in that lab, where all of the research had been related to electromagnetism rather than to chemistry. He went down the hall, searching through other labs, until he found what he needed.
    Back in the main lab, carrying the beaker with the note inside it, he entered the gate and approached the point of transmission. He threw the object through the energy field as if he were a man stranded on an island, throwing a bottled message into the sea.
    It did not bounce back to him.

    —but the brief vacuum was followed by a blustery inrush of hot wind tainted by the faintly alkaline smell of the desert.
    Standing close at her side, holding fast to her, delighted by Stefan's magical departure, Chris said, "Wow! Wasn't that something, Mom, wasn't that great?"
    She did not answer because she noticed a white car driving off state route 111, onto the desert floor.
    Lightning flared, thunder shook the day, startling her, and a glass bottle appeared in midair, fell at her feet, shattering on the shale, and she saw that there had been a paper inside.
    Chris snatched the paper from among the shards of glass. With his usual aplomb in these matters, he said, "It must be from Stefan!"
    She took it from him, read the words, aware that the white car had turned toward them. She did not understand how and why this message had been sent, but she believed it implicitly. Even as she finished reading, with the lightning and thunder still flickering and rumbling through the sky, she heard the engine of the white car roar.
    She looked up and saw the vehicle leap toward them as its driver accelerated. They were almost three hundred yards away, but were closing as fast as the rough desert terrain permitted.
    "Chris, get both Uzis from the car and meet me at the edge of the arroyo. Hurry!"
    As the boy sprinted to the open door of the nearby Buick, Laura raced to the open trunk. She grabbed the canister of Vexxon, lifted it out, and caught up with Chris before he had reached the brink of the deep, naturally carved water channel, which was a raging river during a flash flood but dry now.
    The white car was less than a hundred and fifty yards away.
    "Come on," she said, leading him eastward along the brink, "we've got to find a way down into the arroyo."
    The walls of the channel sloped slightly to the bottom thirty feet below, but only slightly. They were carved by erosion, filled with miniature vertical channels leading down to the main channel, some as narrow as a few inches, some as wide as three and four feet; during a rainstorm, water poured off the surface of the desert, down those gulleys to the floor of the arroyo, where it was carried away in great, surging torrents. In some of the down-sloping drains the soil had washed away to reveal rocks here and there that would impede a swift descent, while others were partially blocked by hardy mesquite bushes that had taken root in the very wall of the arroyo.
    Little more than a hundred yards away, the car strayed off the shale into sand that pulled at the tires and slowed it down.
    When Laura had gone only twenty yards along the edge of the arroyo, she discovered a wide channel leading straight down to the floor of that dry river, unobstructed by rocks or mesquite. What lay before her was essentially a four-foot-wide, thirty-foot-long, water-smoothed, dirt slide.
    She dropped the canister of Vexxon into that natural run, and it slipped down halfway before halting.
    She took one of the Uzis from Chris, turned to the approaching car, which was now about seventy-five yards away, and opened fire. She saw bullets punch at least two holes in the windshield. The rest of the tempered glass instantly crazed.
    The car—she could see now that it was a Toyota—spun out, turning a full three hundred and sixty degrees, then ninety degrees more, throwing up clouds of dust, tearing through a couple of still green tumbleweeds. It came to rest about forty yards from the Buick, sixty yards from her and Chris, the front end pointed north. Doors flew open on the far side. Laura knew the occupants were scrambling out of the car where she would not see them, staying low.
    She took the other Uzi from Chris and said, "Into the slide, kiddo. When you reach the canister of gas, push it ahead of you all