Thirty feet below the levee, inside the arched limestone drainage gallery that ran beneath the eastern wharves, the roar of the river was muffled to a deep, underground thrum that sounded like an iron drum beaten inside a tomb. The air here was warm, damp, and stale, filled with the choking silt stench of anaerobic mud, rotting timber piling, and the chalky tang of crumbling pipe lime flaking from the ancient Roman mortar joints.
Imran Bell walked along the slippery center flat stone slabs. He held his oil lantern low so the yellow circle of light swept across the wet stonework floor. Two paces behind him, young Tavi carried a wooden case filled with corked glass collection tubes and a rolled canvas notebook. Every few yards, Imran paused. That brought the lantern close to the curved vault walls where thousands of small, copper-shelled lantern beetles clung in dense, shivering clusters.
‘Notice their orientation, Tavi,’ Imran whispered, his voice low so as not to disturb the insects. ‘A healthy colony in a quiet drain spreads evenly across the ceiling, feeding on the gray sulfur mold. But look at these clusters. They have abandoned the lower four courses of stone fully. They’re crowding into the crown of the arch, head-down, with their wing cases raised.’
