Forgotten Island

In the Philippines during the 1990s, Jo Yuson presents a story to her class about the forgotten island of Nakali and the dreaded Manananggal. When a classmate mocks her, Jo attacks him and is sent to the principal's office, where she meets Raissa Molina, a classmate who had defended her. Jo invites Raissa to a sleepover with her grandmother, Fatima, who tells them about her travels to Nakali. The girls become best friends, making matching charm bracelets that represent significant moments in their friendship. Fatima later dies of old age, leaving Jo heartbroken.

After graduating high school, Raissa reveals that she is attending Caltech in America, disappointing Jo. At Raissa's farewell party, Jo overhears Raissa's mother expressing her disapproval over their friendship. Jo and Raissa sneak out to the beach, where Jo discovers a magical sand dollar that serves as a portal to Nakali. Despite Raissa's hesitation, they enter together, awakening the next morning with no memory of the previous night. Raissa discovers half of her head shaved and that she has grown wings belonging to Manang, a Manananggal, who attacks them. They escape with help from Batiba, a Batibat, who offers to return them home in exchange for their bracelets and the memories attached to them. The girls refuse and flee with Raww, a were-aspin who claims to have hung out with them the previous night and becomes their guide.

At a market, the trio meet Bungi, a Tiyanak, who tells them that the "Jewel of the Sea" they seek was stolen by a Duwende king. Their search leads them to Mermahn, a Kataw who claims the sand dollar is in his kingdom. Feeling excluded, Raww lashes out until Jo reassures him and shares her fear of being abandoned by Raissa. Following Raww's suggestion, Jo takes them to a Kapre village, where they learn that they had previously saved the villagers from Manang, after which Raissa stole her wings. Manang attacks again, separating Bungi from the group. After escaping, the group learns that Mermahn lied about the sand dollar, while Raww reveals that he works for Batiba, who is actually a memory demon who lives through the memories of others, which she steals from people in exchange for sending them home. He also admits that he had lured Jo and Raissa to Batiba the previous night, after which they relinquished their memories of their time in Nakali.

Batiba recaptures them and restores their memories, revealing that Jo, afraid of losing Raissa, had hidden the sand dollar the previous night to prevent them from being able to return home. Furious, Raissa leaves to retrieve the sand dollar, ending their friendship. Manang attacks Raissa and reclaims her wings, but Raissa informs her that Batiba has stolen from her. Jo then reveals that she offered Batiba her memories of their friendship in exchange for saving Raissa. Raissa is sent back to the Philippines, while Jo stays behind. Back on the beach, a heartbroken and remorseful Raissa adds a leftover firecracker to her bracelet, sending her back to Nakali. Reconciling with Raww, she enters Jo's fading memories and admits how much their friendship shaped who she is, reconciling with her. Manang arrives, but Batiba, finally understanding the value of memories, willingly returns her stolen memories, causing Manang to become docile. Finally accepting Raissa's decision to attend college overseas, the girls head home while Batiba finally goes outside.

Years later, Jo, now a successful graphic novelist, visits Raissa at Caltech to promote a book she has published based on their adventures. Before returning home, the two use their bracelets to reopen the portal so they can visit Nakali once more.