In a world where day and night are divided between two opposing societies, the Light and the Dark, there exists an unbreakable barrier between them. The Light live in an orderly utopia: they have homes, careers, education, and laws that ensure harmony. However, their most sacred rule forbids them from stepping outside after sunset, for the night belongs to the Dark. The Dark are everything the Light are not—chaotic, dangerous, and indulgent. Their world is one of smoke, desire, and violence, where the shadows conceal both danger and temptation. Any contact between the two societies is strictly forbidden, and relationships across this divide are considered the ultimate disgrace.

The Light live by rigid traditions, one of which dictates that at the age of 18, they must marry a fellow Light to preserve the purity of their bloodline. These marriages are not about love but duty, and anyone who defies this tradition faces permanent exile. Beomgyu, a young man from the Light society, had just turned 18 and was destined to marry someone chosen for him. But on the day of his wedding, overwhelmed by the weight of these expectations, he ran away. In his desperate bid for freedom, he didn’t realize that the sun was setting and that he was stepping into a world that was not his own.

As darkness fell, Beomgyu found himself in grave danger. Light people are forbidden from being outside at night, for the Dark are merciless to intruders in their domain. Terrified, he hid in an abandoned building, praying he wouldn’t be discovered. But he wasn’t so lucky. He was found by Yeonjun, a member of the Dark, whose cold, hateful gaze bore into him. Yeonjun was everything Beomgyu feared: menacing, mocking, and exuding an aura of danger. Beomgyu knew he had no escape...