In 2002, Meilin "Mei" Lee, a spirited 13-year-old girl of Chinese-Canadian descent, lives in Toronto. She takes on the responsibility of helping maintain her family's temple, which honors their ancestor, Sun Yee, all while trying to uphold the expectations of her strict and protective mother, Ming. Despite her efforts, Mei keeps her personal interests under wraps, including her strong admiration for the boy band *4Town, which she shares with her closest friends Miriam, Priya, and Abby**.
A pivotal moment arises when Ming discovers Mei's crush on a local convenience store clerk, resulting in an embarrassing scene in public – one that even catches the attention of school bully Tyler. Following this, Mei experiences a vivid nightmare about red pandas, and the next morning, she wakes up transformed into one. In a panic, she hides this secret from her parents, soon realizing that her transformations occur during heightened emotional states, although her hair remains strikingly red.
Initially, Ming misinterprets Mei's transformation as a sign of her first period but soon uncovers the truth after another embarrassing incident at school prompts Mei's transformation. Mei learns from her parents, Ming and Jin, that this unusual ability was granted to Sun Yee for the protection of her daughters, and this transformation has been inherited through generations of women in their family. However, in today's world, it has become a source of complications, requiring Mei to perform a ritual during the next Red Moon to seal away her red panda spirit.
As Mei’s three friends come to terms with her extraordinary transformation, they embrace it, and Mei finds that focusing on her friends aids in managing her inner red panda. With the upcoming *4Town concert drawing near, Ming refuses to let Mei attend, which prompts the girls to secretly fundraise for tickets at school, even using the newfound popularity of Mei’s red panda form to do so. The plot thickens when Mei agrees to attend Tyler's** birthday party as the red panda to secure the last ticket to the concert. Heartbreak ensues when she learns that the concert coincides with the night of her ritual.
In a fit of rage sparked by an insult from Tyler, Mei loses control and ends up frightening the other children at the party. This leads to a confrontation with Ming, who blames Mei’s friends for leading her astray. Overwhelmed by shame and fear, Mei struggles to defend her friends against her mother’s accusations.
As tension mounts, Mei's grandmother Wu and her aunts arrive to aid her in the ritual, much to Ming's consternation. During her preparations, Jin discovers videos of Mei and her friends having fun in their red panda form, encouraging her not to feel ashamed of who she is. When the ritual commences, Mei makes a bold choice; as her red panda form is about to be sealed, she opts to keep her powers instead and rushes to the concert at SkyDome.
Reunited with her friends, who reassure her following the earlier altercation, they also discover that Tyler shares their enthusiasm for *4Town**. However, chaos erupts when Ming, in a fit of rage, transforms into a massive kaiju-sized red panda after Mei escapes the temple, disrupting the concert in an attempt to take her daughter back.
An emotional clash unfolds between Mei and Ming, leading to an accidental blow that knocks Ming unconscious. The supportive aunts break their talismans, allowing them to summon their own red panda forms to help bring Ming into a new ritual circle. Joined by her friends and *4Town**, they sing to complete the ritual, transporting Mei, Ming, and the other women into the astral plane.
In this otherworldly moment, Mei reconciles with Ming and facilitates a healing between her mother and Wu, who bears scars from their tumultuous past. While the other women choose to seal away their red pandas in new talismans, Mei bravely decides to embrace her abilities, much to Ming's eventual acceptance that her daughter is charting her own unique path.
Ultimately, as the Lee family endeavors to raise funds to repair the damages from the concert, the relationship between Mei and Ming strengthens. Mei successfully balances her responsibilities at the temple—where her red panda form is now a cherished attraction—with time spent with her friends, and a budding friendship with Tyler, creating a beautiful harmony in her life.
