Twenty ago, Cargo Flu swept the world.

The City lives on as the shadow of a former metropolis, but growing again, even thriving, using intensive salvage-machinery, spare parts, even wire and gasoline harvested from the wreckage; planned and managed with rigidly enforced rules and regulations. City life is pleasant, not so different from life before-so long as you stay in line.

Miles outside the City, in the wild areas, refugees from the early chaos settled into a small community, living off the land, farming and ranching. They are modestly successful. But it's a hard life, agriculture done the ancient way, without mechanical or electrical power. And it's precarious, imperiled each day by a crippling injury, a life-threatening infection, a crop-destroying blight, or the frailty of advancing age.

Now there are people anticipating war, clever people who think it might be useful, and who don't want to come in second. Yet the remains of the world are fragile. Salvage is beginning to run out. And the great equalizer, Cargo Flu, is still out there, lurking in forgotten debris.

Four people are groping for the right questions. Two have somehow lost their past, and their futures are bleakly empty. But the four are drawn together, and for a time become friends. New possibilities open to them, ways to build a new world over the ruin of the old.

But they are trapped. Not all tyrants have a name. And the hardest Cage to escape has bars that can't be seen.