Episode Summary
Jiang Si's secret identity as a Saintess is threatened as Du Er wants her to return to Southern Wu. She faces suspicion from the Grand Princess, leading to Madam Xiao's death. To protect her family, Jiang Si creates a rift with them. Madam Duo confesses her past crimes and is sent to the Crown Prince's residence for protection.

Spoiler Alert
In this episode of "Si Jin", the drama intensifies as secrets and loyalties are tested.
Returning Home and Hidden Identities: Yu Qi and Jiang Si prepare to visit Jiang Si's family with a mountain of gifts, showcasing Yu Qi's deep affection for her. However, their happy moment is interrupted by the appearance of Du Er, who reveals he knows Jiang Si's true identity as a Saintess and wants her to return to Southern Wu. Jiang Si resists, not wanting to leave her current life, but Du Er is persistent, vowing to wait until she's ready to return with him.
Family Matters and Old Wounds: The next day, Yu Qi and Jiang Si officially visit her family. Jiang Si's family, especially her grandmother, are very respectful, acknowledging Jiang Si's new status as a princess. While Jiang Si's maid, A'Man, packs her belongings for the move to the prince's mansion, she is emotional. Jiang Si reassures her that her uncle's home will always be her family home. Jiang Si's sister, Jiang Yi, gifts her a handmade quilt and Jiang Si confides in her about the tragic events of Zhu Ziyu's wedding night, where he killed Cui Mingyue and then died in a fire. It's implied that Zhu Ziyu's actions were to protect his child from Cui Mingyue, who had been harming the Jiang family.
Romance and Revelation: Back at their home, Yu Qi tries to comfort a slightly melancholic Jiang Si, promising frequent visits to her family. He then surprises her with a romantic gesture in the courtyard.
Intrigue and Suspicion: The Grand Princess learns that Madam Duo personally guided Jiang Si to the Imperial Physicians to obtain medicine for Princess Fuqing. Suspicious of how Jiang Si managed to gain Madam Duo's trust, the Grand Princess orders her surveillance and eventual capture. She also suspects Jiang Si's connection to Southern Wu and assigns her trusted subordinate, Shi Jiu, to monitor her.
Danger and Sacrifice: While Yu Qi and Jiang Si are out, they notice they're being followed. Jiang Si suspects the Grand Princess is onto her. Fearing for Madam Duo and Madam Xiao's safety, she sends people to protect them. Madam Xiao and Jiang Pei are attacked by soldiers, likely sent by the Grand Princess. Madam Xiao sacrifices herself to allow Jiang Pei to escape.
Desperate Measures and Heartbreak: Jiang Pei returns alone, bringing the devastating news of Madam Xiao's death. Jiang Si, realizing her identity will eventually be exposed, decides to take drastic action. She uses Jiang Anmou's constant requests for Yu Qi's help as a pretext to create a rift with her family, aiming to protect them from the fallout of her true identity.
Alliances and Escape: Madam Duo meets with Du Er, who proposes creating a border conflict. This would force Yu Qi to return for his birthday, taking Jiang Si with him, making it easier for her to return to Southern Wu. The Grand Princess's guards attempt to capture Madam Duo, but Du Er and Long Dan intervene, rescuing her.
Forced Separation and Confession: Back at the prince's mansion, Jiang Yi and Jiang Zhan arrive, deeply saddened by the forced estrangement. Jiang Si, however, maintains a harsh facade to protect them. Meanwhile, the Grand Princess searches the palace for Madam Duo to no avail. Madam Duo finds the Empress and Princess Fuqing, confessing to poisoning the late Empress and causing Princess Fuqing's blindness. Following Jiang Si's plan, the Empress sends Madam Duo to the Crown Prince's residence.