In an accident, Lin Yi was transported to an imaginary ancient time, and paradoxically she became the nominal sister-in-law of her boyfriend Gu Yuan.
When modern memory collides with ancient identities, when the identities of "girlfriend" and "sister-in-law" overlap, the twin brothers' preference and suspicion go hand in hand. Is this love and hate that started in a misplaced time and space an old relationship that cannot be broken, or has she fallen into a trap set by the Gu brothers that transcends identity and time?
"Sister-in-law, how can I say 'sister-in-law'?"
