Humanity transmutes into light and time-travels at the same exact second, leaving behind only Lu Chuan, a telecommunication engineer who is repairing equipment on a hundred-meter signal tower. After modern civilization stops running, Lu Chuan builds a small survival circle with animals he rescues one after another while tracking the otherworldly signal received by the control tower, and finally discovers that all of humanity is still alive, and opening the return channel might bring unknown threats back to Blue Star.