The change of watch should have been quiet. The old watch was meant to pass its lanterns and report the ridge lamps; the new one would take the outer rail while the tired officers went down to eat. Captain Han Yue stood beneath the central signal post with the roster in one hand and a tin cup of tea in the other. She had not drunk from it yet.
Shen Yan was checking the straps on his hammer when the nearest lamp flickered.
It blinked once, went dark, and returned with a pale red glow. The officer at the west post lifted his head. Before he could call out, a black line appeared beyond the barrier, hanging above the slope of scorched grass.
Yan stared. The line was narrow and straight, like a cut in a sheet of paper. There was no paper, no wall, and no shadow that could have made it. It hung in the open air, a short distance beyond the red barrier. Blue light moved inside it, too dim to reach the ground.
The lamp steadied.
“Sound the alarm,” Han said.
The watch officer struck the brass plate three times with his baton. The alarm rolled down the ridge, then came back from the station walls. Men and women ran from the steps and side rooms, carrying bows, spears, and coil rope. No one shouted questions as they arrived. The ones who knew the platform took their stations. The others looked to Han.
