Three Short, One Long

The world wasn't blown up. It slowly went quiet. Grey fog pressed in from the horizon, cities went dark one by one, people fell silent row by row. In the end, only a few cast-iron furnace rooms in the underground tunnels still glowed. As long as the fire burned, humanity endured. Someone heard a sound from deep in the tunnels— three short, one long. Three short, one long. The rhythm was like a heartbeat, like a cast-iron hammer striking an anvil. It wasn't an echo. It was a signal. So the survivors built a ship, loaded it with iron, seeds, hammers, and a red flag, and flew into the grey fog toward the source of the signal. Thirty-nine years. Three generations. Some were born on the ship, some died on it. The furnace never went out. They arrived. Beneath their feet was iron. The ground had spiral patterns. The stars in the sky lit up one by one. The source of the signal wasn't someone else. It was themselves. —Going home doesn't require someone to call you. Three short, one long. The furnace never stops, and neither do the people. — Description from novelcodex.org