Matilda finds Glum thrashing under the couch in the pool house lounge, blood and feathers everywhere. She tries unsuccessfully to pull the massive dog away. Tatum arrives, and together they move the couch, but by then the screaming has stopped. Glum runs toward a lone surviving duckling, Cotton, by Matilda’s feet. Tatum restrains the dog while Matilda rescues Cotton, taking her to a bathroom. Matilda, Tatum, and Brock clean the bloody scene, and Matilda wraps the nine dead birds for burial. Meer vehemently denies leaving the door open and runs off upset. Tatum calls the Farm Institute, which agrees to take Cotton. During their drive to deliver the duckling, Matilda reflects that Hidden Beach will never be her home, seeing the castle’s neglect and decay as evidence that something is deeply wrong with the family.

After dropping off Cotton, Tatum drives to a hardware store. He reveals that Glum attacked the birds because she was starving—Kingsley has given them no money since March, and though Tatum had assigned buying dog food to Meer, it went unpurchased for two days. Overwhelmed by guilt and the strain of supporting the household, Tatum breaks down, lamenting that he cannot save money to leave. Matilda comforts him, and they share a long, passionate kiss in the rain that dissolves their anger. In the hardware store, Matilda uses her own money to buy four large bags of dog food. Back at Hidden Beach, they feed Glum and swim in the ocean together.

That evening, Matilda and Tatum find June and a puffy-eyed Meer eating vegetable soup. June thanks them for cleaning but scolds them for taking the car without permission. Later, Matilda confronts June about neglecting Meer, pointing out she was completely unaware of 10 birds living in the pool house. June defends herself, claiming she gives Meer freedom and that everything she does is for him. She accuses Matilda of having narrow views about motherhood and of not criticizing Kingsley. June asks for wine, then begins a long confession: Matilda’s arrival has forced her to see her supposedly liberated life is actually one of complete financial and social dependency on Kingsley. She compares herself to Tipper Sinclair, realizing she is essentially a housewife, just in a different form. June reveals she has no legal claim to the property and leaves Matilda wondering whether Kingsley ultimately wanted a traditional housewife after all.

At midnight, Matilda goes to Tatum’s room and asks to sleep beside him. She has never shared a bed with anyone before. They settle in, and Tatum brings up an earlier comment she made about not inspiring devotion. She explains this belief stems from her mother leaving and her friends abandoning her after her breakup with Luca. Tatum confesses he was devoted to her from the moment he saw her, calling her a supernova. He says that his initial rudeness was fear of the intensity of his feelings and insists his devotion is a fact she should not doubt. She kisses him in response. The next morning, he is gone but has left a note saying their concert is that night.

That evening, Matilda and Tatum ride the scooter to Oak Bluffs. Tatum explains he knows the door staff from his soccer days, so her lack of ID will not be a problem. When Matilda presses about his estranged friendships, he stops, kisses her, and whispers the reason: June does not want him to see his friends. He says June has a good reason and asks Matilda to drop it for the night. She agrees. They dance at the concert and afterward share a passionate kiss on the quiet street.

Back at Hidden Beach, Matilda and Tatum kiss until they hear June unlocking Bone Tower. They separate and go to their rooms. Unable to sleep, Matilda’s mind races with questions about Kingsley. Determined to find answers, she sneaks to the mudroom while June is baking and takes the keys from the Spoils of War box. She enters Bone Tower, exploring the ground floor full of paintings and the second floor containing June’s weaving studio and herb laboratory. On the third floor, she unlocks a bolted door and enters Kingsley’s two-story studio. Among many canvases, she finds a recently painted portrait of herself asleep, titled Melinoe, Bringer of Madness.

Matilda examines the painting, which depicts her in her UC Irvine sweatshirt with goblins from Kingsley’s sketchbook under her bed. She realizes the painting’s existence proves Kingsley painted it at Hidden Beach, not in Italy. Her vivid “dream” of Kingsley visiting her room and calling her Melinoe was real. This confirms Kingsley made the sketchbook drawings, including the piranha plant, and has been hiding at Hidden Beach the entire time, lying in his emails about being in Italy.

Matilda explores further and sees a large painting-in-progress depicting the Sinclair cousins, with only Johnny painted in, covered in ash. She climbs the spiral staircase to the fourth floor, a messy room with locked windows. There, lying on a bed with an IV drip, she finds her father, Kingsley Cello. He looks wasted and sick. She has a series of realizations: This is where June spends her days, why Meer is not going to college, why Tatum is isolated, and why no visitors are allowed. Something is terribly wrong with her father.

Matilda wakes Kingsley, who immediately begs her to cut his IV line, claiming June is a “witch” who drugs him to keep him weak and forces him to paint. He says he refuses to drink what June brings and relies on pre-packaged food from Brock. He recognizes Matilda and admits he has been watching her from his window. He gives her a folded drawing for Meer. His lucidity fades as he calls her Melinoe and rambles about seeing the Beechwood fire, about June being a “witch,” and refusing doctors because their pills would interfere with his artistic vision. When he grabs her hand and bellows for scissors to help him escape, Matilda pulls away, frightened. She flees down the stairs, then returns to lock and bolt the studio door, trapping her father inside again.

Matilda packs her essentials and runs from the castle into the rain. Tatum chases after her. She confronts him: Kingsley is locked upstairs. Enraged that he and the others lied to her for weeks, she accuses him of betrayal. Tatum confesses they were all hiding the secret and that Meer brought her to Hidden Beach because he needed support and could not handle the situation alone. He explains the progression of Kingsley’s dementia—paranoia, rages, refusal of medical care—which led them to lock him in the studio for safety. They had to restrain him to insert an IV port for hydration. This is why neither Tatum nor Meer are going to college. Matilda connects her sedation by June to Kingsley’s earlier escape to her room. Tatum confirms this and reveals they later bolted the door and removed Kingsley’s knife. When Matilda accuses them of profiting from Kingsley’s paintings, Tatum counters by questioning her own motives. She denies wanting money and runs off.

At three o’clock in the morning, Matilda arrives at Holland’s house. Holland calms her, provides dry clothes, and makes coffee and cake. After listening patiently to Matilda’s entire story about discovering Kingsley locked in the tower, Holland says she has information to share and reveals she has met Meer before.

Holland recounts her family history: Her great-grandparents had three sons, Harris, Dean, and Kincaid Sinclair. Their father pitted them against each other. Kincaid, an artist and a disappointment to his father, left the family and reinvented himself in Italy as Kingsley Cello. Holland reveals that Matilda and Meer are Sinclairs, making the Beechwood fire victims their cousins once removed. Kingsley maintained minimal contact with his brothers through his sister-in-law, Tipper, and built Hidden Beach near Dean’s summer home, close enough to see Harris’s house from his tower. Matilda recalls the unsent note to Harris she found, connecting the Narnia nicknames.

Holland explains that a year ago, when Kingsley’s dementia became apparent, Tipper found him wandering and told Meer his true family history. After Tipper died and Kingsley’s condition worsened, an isolated Meer contacted Holland and Mirren on social media, planning to meet on the island. Meer could not reach Matilda through other channels, so he faked emails from Kingsley and offered her a painting to lure her to Hidden Beach for support. Their plan was derailed by Mirren’s death and Meer’s fear of revealing the tower secret. Matilda retrieves the note Kingsley gave her for Meer. It contains a drawing of young Meer and a cruel message stating that while Meer will inherit everything, he is a “witchling” and betrayer who does not deserve it, expressing Kingsley’s pain at becoming a disappointed father like his own.

After sleeping through the day, Matilda wakes at night determined to return to Hidden Beach and make her father see her for who she truly is. On her way, she receives remorseful texts from Tatum, who now knows the Sinclair history. Softened, she replies they can talk later. At the castle, she avoids Tatum and uses the keys to enter Bone Tower. She goes to June’s studio and steals a pair of scissors.

Matilda enters Kingsley’s hot, smelly room and wakes him. He is paranoid and hostile, calling her “Witchling” and mocking her. He rambles about wanting money, his dead grandchildren, and freeing Meer’s birds during a brief escape when Meer left the door unbolted. Suddenly lucid, he asks Matilda to cut his IV line so they can go downstairs and talk about her and his paintings. Believing him, she uses the stolen scissors to cut the tube. Kingsley gets up, changes into clean clothes, and leads her toward the spiral staircase.

As soon as they reach the studio floor, Kingsley attacks Matilda, pinning her arms and taking the keys from her pocket. He holds the scissors to her throat, revealing his request was a ruse to escape and telling her he owes her nothing. Glum rushes in barking. Matilda stomps on Kingsley’s foot, causing him to release her. He hits Glum with the heavy key ring, then runs out and locks the studio door. Matilda pounds and calls for help but cannot reach anyone. June eventually appears and unlocks the door. A frantic search begins with the group splitting up. On the beach, Tatum tells Matilda there is no saving her father from his illness. Returning to the castle, a sobbing Meer meets them. June furiously blames Matilda for letting Kingsley out. Meer whispers that he too wanted to free his father, then reveals June found Kingsley and he is dead.

At the pool deck, they find Kingsley’s body floating face down in the swimming pool. June sits by the edge, soaked from the waist down. Brock, also wet, explains he heard a noise from June and found her in the pool, unable to turn Kingsley over. He determined Kingsley was already dead. In a very low voice, Brock reveals June gave Kingsley a sedative. June overhears and orders him to stop talking. She takes charge, forbidding anyone from acting until she decides how to handle the situation.

In the kitchen, Brock explains the full story. June found Kingsley in the office searching for his confiscated phone. He became violent, so she injected him with a powerful sedative. He pushed her down and ran outside before the drug took full effect. They surmise he stumbled and passed out as he reached the pool, falling in. Against everyone’s wishes, Matilda calls the police.

June screams at Matilda, blaming her for Kingsley’s death. When the police arrive, June’s demeanor changes completely to that of a grieving, helpless widow. Matilda is filled with anger and suspicion, wondering if June murdered Kingsley, but says nothing for Meer’s sake. The family tells the police Kingsley became violent, June sedated him, and he accidentally drowned. June asks the police to keep details from the papers. An ambulance removes Kingsley’s body. Matilda reflects that in his final moments, Kingsley escaped again. As the sun rises, June leaves for the funeral home, and the others return to the quiet castle.