They were within twenty feet of a similar craft, dark except for orange lights bow and stern like the lanterns of ships sailing well-traveled routes. In the glow from the vessel in which he rode, Vibulenus could see that there were half a dozen yellow-clad forms in the other vehicle.

The interior lighting faded or was replaced by an image like those of the mythic battles in the Recreation Room. There was no fantasy in this, however: Decimus Helvius crouched within walls of stone which were hinted rather than being fully limned. He held a naked sword in his hand, and the expression on his face was the stony determination the tribune had glimpsed that afternoon when the enemy, shouting in anticipated triumph, charged up the hill at the Tenth Cohort.

Behind Helvius squatted Grumio and Augens. The former's left biceps was bandaged-his shield must have been hacked off his arm during the fighting. Augens had no obvious injuries, but he had set his helmet between his knees and was squeezing the bronze with a fixed intensity that suggested he was in pain.

Neither of the common legionaries was looking toward Helvius or the open end of the passage. After a moment's surprise, Vibulenus remembered that none of the deserters could see anything in the lightless cave.

It could have been a trick; but it was easier to believe the trading guild could see through stone than that it would bother with trickery so pointlessly elaborate.

"No trouble," repeated the Commander in oily satisfaction. "The rest of your fellows are gathered in the Main Gallery to watch the demonstration, but I thought you might as well see it with us."

The image of Helvius turned and said something unheard to his companions.

"You should realize, Gaius Vibulenus Caper," continued the Commander's voice, "that if you had not proved yourself to be an unusually valuable asset of my guild, you would be viewing the demonstration from the ground where we picked you up. But no asset is so valuable that it will be permitted a second lapse in judgment as great as the one you made tonight."

The voice laughed. Technically, the laugher was "correct," as the Commander's diction always was; but instead of humor, the sound had the mechanical hollowness of blood dripping from the neck of a slaughtered hog.

"Since we're here," the Commander added, "you can watch over the side as well."

The tribune thought no, I'm afraid of heights, but his tongue could no more have articulated the words in this company than he could have flown home by waving his arms. Without speaking, he stood and leaned over the side. The vehicle remained as steady as an unsprung farm cart.

The vision of the three deserters continued to hang before the tribune. That calmed him more than did his grip on the coaming, though he was clinging fiercely enough to dent copper. The sky retained enough ambient light to limn the grosser features of the landscape, but it took some moments before Vibulenus recognized the circle glimpsed through the ghostly torso of Helvius as the sinkhole. The hole seemed to be the size of a medicine ball.

His arms began to shake although the backs of his hands ached with the violence of his grip.

"What are we-" started Niger, less cowed or less controlled than his fellow centurion.

Magenta fire pulsed in stroboscopic succession from the underside of the other hovering vehicle.

The air slapped after each bright surge, but the pulses followed one another a dozen times a second, faster than ears or eyes could detect the separation. Vibulenus' bowels started to loosen at the low-pitched hum, while the green complement of the laser flux rippled across the back of his eyes when he blinked.

The pulses slanted, not toward the cave mouth as the tribune expected but rather into the rock wall nearby. The limestone split apart in gouts of white, glowing chunks-not molten, but burned to raw quicklime that gnawed everything it touched with a caustic vehemence.

Over the flux ravening against the surface lay the image of the deserters, looking up in puzzlement as the cave trembled with the twelve-a-second pulses.

"Stop it!" Vibulenus screamed. Though he turned to the Commander, he could not escape the vision of Helvius, frowning not in fear but curiosity at the sound filling his strait universe.

The tribune must have reached out, but he was not aware of the movement until one of the toadfaced guards thrust him back with the head of his mace. The dull spikes pressed hard enough to break the skin over Vibulenus' breastbone before the Roman's body returned to immediate reality.

The ground exploded as the laser's slow gouging into refractory limestone brought it at last to a stratum through which ground water percolated. The liquid flashed to steam in an instant that shattered the whole face of the sinkhole. Pieces of rock the size of a house lifted from foundations that had held them for fifty million years, then toppled toward the center of the sinkhole.

It must have felt like an earthquake deep within the cave, because Grumio looked up, shouted something, and tried to rise but hit his head on the stone ceiling. Did they think the guild was blocking the entrance to their cave? Helvius dropped his sword and shuffled two steps forward in a crouch, his hands lifted to protect him from the rock he could not see.

The cave roof split, letting the magenta flux play on the interior. Vibulenus screamed, but his mind transferred the sound to the open mouths of the victims dying below.

Grumio was in the beam's direct path. The first pulse gnawed his body to the waist. His legs vaporized microseconds later, before they had time to fall. The legionary's iron hobnails burned with such white sparkling intensity that they looked dazzling even through the coherent pulses of the laser flux. The steel of his sword retained its shape for the instant it took to fall through the beam-belt gone, scabbard gone, and expensive ivory hilt in gaseous mixture with the hand that once wielded it.

The left arm flopped free, shriveling but not in the flux. Its bandage flashed a brilliant reflection of the beam which had vaporized Grurnio.

Augens had started to rise and was not in the angled beam, but his helmet was. Bronze, gaseous or molten depending on how close it was to the center of the flux, spewed in a green flood from the impact of the light.

Reflection from the cave floor, burned white and heated to thousands of degrees by the pulses it absorbed, vaporized the legionary's feet and crisped his legs and lower body to glowing cinders. The rest of him toppled into the flux which devoured him so completely that only splinters of calcined bones reached the floor.

Unlike his companions, Decimus Helvius had time to understand what was happening to him.

The blaze behind the centurion threw his shadow in troll-like distortion down the path of his attempted flight. The beam was angled away from him, deeper into the cave, and it seemed for a moment that he might escape.

Helvius lunged forward, aided by the light though his calves burned black and the bronze studs dropped from the holes they had charred in the leather that protected his thighs. Then the cave roof collapsed onto him.

The laser continued to play on the rockface for some further seconds. Even with his eyes closed, Vibulenus could see his comrade's right foot charring in the dazzle reflected as the flux ate its way far beneath the cave.

The sky-shaking hum ended as the crew of the other vehicle shut off their weapon. A moment later, the echo from the ground ceased also. A violet nimbus around the gunvessel dissipated more slowly, as did the white glow and sound of crackling rock at the point of impact.

Vibulenus sat down. He was crying, though the fact humiliated him. When his eyes were shut, his memory reviewed the instant of destruction, but his overloaded retinas continued to pulse bright green, shrouding the horror somewhat.