My Wife Is So Gentle, She Couldn’t Possibly Be a Demon

She brings the medicinal meal to his lips, her smile as gentle as a spring breeze. He tips his head back and drinks, as if swallowing poison. The prince knows she is a vengeful demon cloaked in tenderness, yet willingly walks into her trap. Then, on an old letter long sealed away, the name of his family emerges. In this contest between husband and wife, which of them is truly caught in the game?