It turns out that amid the crowds and bustle of human society, wondrous and eerie things are happening on the other side, as if there were another "society." It turns out that in the real world, where the sun rises and sets and day gives way to night, beings who are not part of humanity are living their own "lives," as if in another world. It turns out that "death," though present in every mythology and religion yet rarely noticed, coexists with "life," as if the two sustain one another. How exactly does the cycle of life and death work? What keeps the laws between yin and yang in balance? And what force determines what is gained or lost, who stays or goes?