Episode 4 recap: Investigate the truth about Prince Qi's poisoning by Cheng Biyuan.

At night, Butler Pan sneaked into the kitchen to destroy the evidence, but he was surprised to find Cheng Biyuan already ambushed there. She revealed that Butler Pan had put the powdered Shen Si herb into the water and soaked the prince's soup bowl in it, ensuring that the food in the dish remained safe while the bowl became contaminated. Realizing that the situation was exposed, Butler Pan brazenly admitted to his actions, stating that it didn't matter anymore because the prince was already poisoned beyond survival. Cheng Biyuan, however, couldn't escape the implications.

Upon hearing Butler Pan's confession, Prince Qi and his guards, who had been waiting outside the door, confronted him directly with their swords. Butler Pan, shocked to see Prince Qi alive, wondered who ordered the hit. Refusing to divulge any information, Butler Pan chose to commit suicide instead. Prince Qi commanded his subordinates, Cong Tou and Suan Ban, to investigate who was behind Butler Pan's orders.

Liang An'er approached her father, expressing disbelief that Butler Pan would harm Prince Qi under someone else's orders. She vowed to seek revenge on the perpetrator, promising to eradicate their entire bloodline once she discovered their identity. Her father, visibly uneasy, suggested that Liang An'er seek Cheng Biyuan's assistance. The Grand Tutor suggested that Cheng Biyuan be invited to the palace to prepare for the Mid-Autumn Festival banquet. Liang An'er, perceptive of her father's cunning, seemed to understand something.

Upon learning of these developments, Prince Qi grew deeply concerned, suspecting that there was a hidden agenda at play. Meanwhile, Cheng Biyuan was ecstatic and had already started preparations in the kitchen. She planned to create a dish called "Phoenix Pierces Peony" using radishes, intending to dazzle everyone at the Mid-Autumn Palace banquet. Although the dish appeared simple in terms of ingredients, its preparation was intricate, requiring three days to pickle the radishes to a golden color.

That night, Liang An'er entered the kitchen and secretly added a packet of powder into the jar of radishes being pickled by Cheng Biyuan.