Episode Summary
In this episode, the barrier between the human and demon worlds weakens, forcing Wu Zhen and the Wordless Book to repair multiple breaches. Mei Zhuyu investigates a mysterious new drug in the city's red-light district, leading to a disguised, memory-wiped confrontation with Wu Zhen. The Wordless Book's increasingly ruthless nature causes a major conflict between it and Wu Zhen, while Liu Taizhen warns Wu Zhen about the dangers of getting too close to mortals by revealing a painful betrayal from her own past.

Spoiler Alert
A Tale of Two Faces in Chang'an
Episode 13 of Moonlit Reunion begins with Wu Zhen waking up to a thoughtful Mei Zhuyu. He's reading a popular romance book and seems genuinely puzzled about why these stories always treat marriage as the ultimate goal for women, completely ignoring their value and hardships beyond that. Wu Zhen can't help but smile, clearly impressed by his perspective.
The quiet moment is cut short when Hu Zhu rushes in with the Wordless Book. There's trouble. The magical barrier protecting the city is cracking, letting mortals wander into demonic territory and smaller demons slip out. Their boss, Liu Taizhen, is overwhelmed and needs them to help with repairs. As they talk, the Wordless Book notices the medicine and sweets Wu Zhen had prepared for Mei Zhuyu, and a flash of jealousy darkens its expression.
Meanwhile, Mei Zhuyu, suspecting there's more to the previous night's strange new moon, meets up with Shuang Jiang. They head to the city's red-light district to investigate but are stopped by Captain Huang Yi. The captain warns them that Chang'an is on edge because a dangerous illegal drug is making the rounds. He'd love to lock the whole area down to search, but too many powerful people frequent the establishments. Mei Zhuyu pretends to back off but secretly returns, wearing a mask and having taken a voice-changing pill that unfortunately renders him completely mute.
As Wu Zhen finishes patching one hole in the barrier, she finds another that leads directly into a sinister shop that sells human "skins." She quickly seals the breach. Just as she finishes, a drunk man stumbles in, and she has to knock him out. That's when she comes face-to-face with a masked man—the disguised Mei Zhuyu.
They fight briefly, and while Mei Zhuyu senses demonic energy on his opponent, he has no idea it's Wu Zhen.Seizing the advantage, Wu Zhen erases his memory of their encounter and tosses him out of the barrier. She and the Wordless Book work through the night fixing the cracks. It's only the next morning, when they run into Captain Huang Yi again, that Wu Zhen learns Mei Zhuyu was in the area.
Back in the Demon Market, the Wordless Book is cornered by the shadowy Boneless Bone, who once again tries to convince it to join forces. The Wordless Book flatly refuses. Annoyed, Boneless Bone reveals its backstory: its original form was destroyed, and it spent a century hiding in a jewelry workshop just to get back into the world. It taunts the Wordless Book, calling it a waste of potential for an ancient, powerful weapon to be so subservient.
At the same time, Shuang Jiang gets an urgent message for Mei Zhuyu. The reclusive Changxi Palace, which has stayed out of worldly affairs for a century, wants to gather its disciples to deal with the demon problem in Chang'an. Mei Zhuyu, however, feels the palace is too out of touch and decides to continue his own secret investigation.
Overnight, rumors of evil spirits in the red-light district have spread like wildfire, unsettling the men all over the city. The leaders of the Demon Market hold an emergency meeting, but the elders have no solutions. The Wordless Book makes a shocking suggestion: to solve the problem for good, they should just kill every person who has recently visited the district. Wu Zhen is horrified and vehemently objects. Their argument reveals a growing, ruthless side to the Wordless Book that frightens her; she would rather take a risk than harm innocent people.
Later, Liu Taizhen finds Wu Zhen and shares a painful story from her past to serve as a warning. Two hundred years ago, she lived among humans as the "White Snake Gentleman" and fell in love with a scholar. They were happy until he discovered she was a snake demon. He ran away in fear, only to return later pretending he still wanted to marry her, but it was a trap to poison her. Showing Wu Zhen an old scar, Liu Taizhen warns her that people's hearts are as deep and unknowable as the ocean. The closer you get to someone, the more you risk feeling their sharp edges.