Episode Summary
Jian Mingshu hides in Song Qingzhao's room, leading to awkward encounters and Lu Chang intervening by making Jian Mingshu his own book attendant for her safety. While investigating Xie Xu's suspicious meetings, Jian Mingshu has a close call when Lu Wencai searches Lu Chang's room while she's bathing, but Lu Chang manages the situation. Realizing Xie Xu is aware of her presence, Lu Chang secures an official position for Jian Mingshu at the academy to protect her. Meanwhile, Yin Shujun subtly combats rumors about her cold marriage to Prince Rui, and Jian Mingshu learns of a reclusive woman named Tang Sheng living in the academy's back courtyard.

Spoiler Alert
Serendipity: Episode 13 Recap & Spoilers
Alright, so the episode kicks off with Song Qingzhao trying to be smooth. He gets the academy kitchen to whip up a special dinner and brings it to his room, much to Jian Mingshu's delight (girl loves her food!). But, of course, perfect timing award goes to Lu Chang, who knocks on the door right then. Cue panic! Song Qingzhao shoves Jian Mingshu into a closet before answering. Lu Chang's just checking in since Song Qingzhao missed dinner, wondering if he's sick. Song Qingzhao, trying to play it cool, deflects and quickly ushers Lu Chang out. The second he's gone, Song Qingzhao rushes to the closet, and Jian Mingshu practically tumbles into his arms. Awkward!
Meanwhile, in the royal newlywed department, things are... frosty. Yin Shujun notices Prince Rui's room is quiet and decides to redecorate it her way, packing up his stuff. Ouch. Prince Rui's attendant is confused when Yin Shujun's lights go out early, but Prince Rui seems weirdly fine with it, noting that marriage hasn't changed his routine one bit. Yikes.
Back at the academy, Song Qingzhao sets up a separate makeshift bed for himself, letting Jian Mingshu have the proper one. He admits he admires her free spirit. They chat for a bit, but Jian Mingshu conks out pretty fast. Song Qingzhao, however, is wide awake, restless. He ends up grabbing a book and heading outside to read, just like Lu Chang does.
Early the next morning (like, really early for court), Prince Rui is getting ready when Yin Shujun shows up to dress him, stating it's her duty as the Princess Consort. As soon as he leaves, she heads back to her room to catch up on sleep. Prince Rui thinks she's trying to win him over, but his attendant hilariously points out it feels more like she's just checking off a task list. Double yikes.
Jian Mingshu wakes up to find Song Qingzhao just returning, claiming he's an early riser. As he fumbles getting ready for class, Jian Mingshu steps in to help him with his hair (fulfilling her temporary role as his book attendant). It's not the neatest hairdo, but Song Qingzhao seems to treasure the gesture. He then tells her he overheard Xie Xu planning to meet a friend. They decide to investigate and spot Xie Xu meeting a woman. The pair gets on a boat, conveniently leaving behind an academy access token on the shore.
When they sneak back, who should catch them but Lu Chang? He pulls Jian Mingshu aside and reads her the riot act, emphasizing how crucial a woman's reputation is. Jian Mingshu stands her ground – she's there to investigate the case and needs to stay. Lu Chang, realizing he can't just send her away, relents but with a condition: she has to be his book attendant now, and steer clear of Song Qingzhao!
That night, Jian Mingshu starts setting up bedding on the floor in Lu Chang's room, but he scoops her up and puts her onto the bed, saying he'll sleep elsewhere. Where does he go? Straight to Song Qingzhao's room! Song Qingzhao frantically explains Jian Mingshu didn't sleep there the previous night. Lu Chang isn't just there to chat; he brought homemade dumplings filled with aged sour bamboo shoots (a clear sign he's ticked off). Song Qingzhao knows he messed up and forces them down. Lu Chang warns him about gossip and the need for propriety between men and women, emphasizing he doesn't want Jian Mingshu hurt.
Lu Chang ends up crashing in Song Qingzhao's room... and the next morning, they wake up in the same bed. Mortified, Song Qingzhao swears it was just habit. Lu Chang, seeing Song Qingzhao still can't manage his own hair, gives him a helping hand.
Jian Mingshu explores the academy grounds, suspecting the mystery woman might be hiding in the back courtyard area. Lu Chang cautions her that the situation is complex – even if Xie Xu is shady, what about the Wen'an County Mistress (presumably Xie Xu's fiancée or intended)? But Jian Mingshu is driven by wanting to help other women, knowing how vital marriage decisions are for them. Elsewhere, Xie Xu finds out Jian Mingshu is undercover as a book attendant and realizes she's investigating him. His mistress/lover is worried.
Later, Jian Mingshu's stomach is rumbling, so Lu Chang makes her a bowl of noodles – her favorite kind. Aww. Jian Mingshu then sees Xie Xu dropping off clothes for laundry with a certain Lin Da Niang and tries to snoop around but finds nothing and gets splashed with water for her trouble. She heads back for a bath.
While she's bathing, disaster almost strikes again. Lu Wencai barges in with his posse, demanding to search Lu Chang's room for his lost cricket! Lu Chang manages to block the bathroom and hustle them out while Jian Mingshu hides underwater in the tub. Song Qingzhao is pacing anxiously outside. Once they're gone, Jian Mingshu emerges, gasping for air. Lu Chang immediately wraps her in his outer robe, holding her close. It's A Moment™, and Jian Mingshu feels flustered. Lu Chang quickly figures out Xie Xu must have framed him for taking the cricket, knowing Jian Mingshu was there and trying to expose her.
Xie Xu isn't giving up on getting Jian Mingshu kicked out. So, the next day, Lu Chang cleverly recommends Jian Mingshu for an official position helping out at the academy, giving her a legitimate reason to stay. Smart move, Lu Chang!
Circling back to the royal couple: gossip is swirling in the residence about Yin Shujun not being favored. She tells her maid she knows exactly how to handle rumors. She instructs the kitchen staff, via her maid, to prepare more "nourishing" dishes, subtly implying she and Prince Rui are... ahem... enjoying their newlywed status and need the extra sustenance. This completely baffles Prince Rui.
Finally, Jian Mingshu learns from her inquiries in the back courtyard that there's another woman living there named Tang Sheng. She apparently knows how to read but is reclusive and rarely seen.
Looks like Jian Mingshu has a new lead, Lu Chang is playing protector (and maybe feeling something more?), and Xie Xu knows he's being watched. Things are definitely getting complicated!