The back wall shuddered, then a gritty rustle filled the room. A crenelated portion of the wall about two meters square slid back to a depth of half a meter, then drifted to the side. Tark poked his head through the hole for a quick look, then joined us in the basement. "Time is of the essence. gentlemen," He tapped a finger on his radio earphone. "Lone Star has takers exception to the loss of their operatives