Ahead, just outside the blazing lake of light around the building, the air-vent loomed. Wriggling to it, he jerked out his knife and pried at the grilled lid's seal. But then, once again, Ungo was beside him. "Here, let me at it, Jarl!" Heedless of danger, the Jovian surged to full height. His talon fingers splayed through the grill. The broad back, the mighty shoulders, strained and heaved. There was a thin _spang!_ of metal parting. The lid tore free. Jarl gripped his comrade's arm. "Ungo...." "Forget it, Jarl. I understand. Our job is down below." A tightness came to Jarl Corvett's throat. Wordless, he swung his legs over the edge of the vent, lowered himself to full arm's length, and let go. It was a six-foot drop into blackness so ebon that it made the outer night almost seem bright. Twisting, he crawled a few feet along the horizontal conduit that ran from shaft to building. Ungo's gruntings drifted down as he wedged his great body through the hole. Then, with a thud, the Jovian, too, had landed. The other five followed, one by one. "This way!" Jarl whispered. "The tube leads straight to the blower room." Ghost-silent, they crept through the murk for what seemed miles. Fine dust rose about them in a choking haze, and there was an acrid stink of tanaline and _jeol_. Tiny _bulaks_ chattered their fright, scampering from the raiders' path. The suction of the Banx unit at the tunnel's other end tugged at hair and tunics in a gusty, whistling gale. Then, feeling ahead, Jarl touched a screen. He halted; half-turned. "We've made it. We're inside." Twisting, he ran his hand over the tube's side wall till he found the cleaning hatch. His searching fingers touched the bolt. He worked it round. The hatch swung open on creaking hinges. Knife in hand, Jarl slid out into the blower room, with its looming bulk of Banx unit transmuters and converters and compressors. A dim rectangle on the right marked the ramp to the floor above. Cat-footed, flat to the wall, Jarl moved up the incline, the raiders at his heels. A faint scuff of sound whispered in the stillness. Ahead, out of a cross-corridor, a Martian _fala_ in the blue tunic of a Federation guard moved into view. Jarl froze, not daring to breathe. The guard crossed the ramp, not pausing, and went on down the corridor out of sight. The shuffle of his steps faded and died. Jarl slid forward again till he reached the passage, then halted. Taut-nerved, he waited, listening. Voices came dimly. Jarl lowered himself to the floor. Ever so cautiously, he peered around the corner. * * * * * Far down the hall, the guard stood chatting with one of his fellows. A moment later, breaking off, he turned and started back towards the ramp again. Jarl drew back. Rising, he wiped the sweat from the palm of his knife hand, then crouched waiting. The sound of the _fala's_ footsteps drifted to him, closer and closer. Jarl sucked in air.