Day fifty, before the sky was fully light, the beacon still burning. Ten-odd minutes past the agreed time, rotors sounded over the far end of the street - an old helicopter, searchlight on, hovering low over the road out front. The man in the cabin doorway checked the coordinates with you twice, shouting over the rotors, and said the signal came off this beacon, clear as anything. He offered no encouragement. He just cleared a space in the cabin and told you to take what mattered. You looked back at the building once, and pulled the door shut.

Day fifty. The beacon on the terrace has not been off since last night; the needle on the battery gauge steps down notch by notch. After first light, the beat of rotors comes down low overhead. It is him. The helicopter hangs above the rooftop, its searchlight on the terrace; he waves from the cabin, says there is room, bring only what you can carry. You lock the basement door and tuck the key back above the frame - in case anyone else comes. Then you go back up to the terrace.

Day fifty. The beacon on the roof platform stayed on all night, the wind snapping the cable against the rail. The sun had just come up. A helicopter hung over the road outside the gate, its searchlight on the warehouse wall, its rotors whipping up the dust. The man who came is in work clothes, the same one from the channel. He looked up at the antenna on the platform and said: no wonder the signal was so steady. There is still plenty on the shelves. You did not count it again. You pulled the roller door down and climbed aboard.