Zed, Milo Manheim, Addison, Meg Donnelly, Eliza, and Willa have recently completed their first year at Mountain College. Throughout the year, both Zed and Addison devoted a great deal of their time and energy to their respective sports—Zed focusing on football and Addison excelling in cheerleading. Their intense focus on their athletic pursuits meant they had little opportunity to spend quality time with each other or their other friends. As summer approaches, Zed intends to attend a football camp to earn the coveted "first string" position, while Addison plans to go to a cheer camp to bolster her chances of becoming cheer captain.
The group embarks on a road trip to their summer destinations, but things take an unexpected turn when a mysterious energy surge causes Zed’s Z-band, a device he wears, to malfunction. This malfunction results in their car veering off the road, leaving the teenagers stranded in an unfamiliar and possibly dangerous area. In the chaos, they decide to split up to seek help, each encountering their own set of challenges.
Zed encounters a new group of monsters called the Daywalkers, led by the formidable Nova, while Addison comes face-to-face with Vampire monsters, led by Victor. Both groups are embroiled in a bitter rivalry over a dwindling resource called Blood Fruit, which is essential for their survival. Nova and Victor, each driven by their own elders’ demands, are under enormous pressure to secure as much Blood Fruit as possible—sometimes resorting to drastic measures. Their ongoing conflict escalates as both groups arrive simultaneously at a Blood Fruit orchard, but find the gates sealed shut.
While searching for a way into the orchard, the Daywalkers and Vampires settle into an abandoned camp named Rayburn, where they gradually begin to forge an uneasy alliance. Meanwhile, Zed, Addison, Eliza, and Willa act as mediators, hoping to broker peace between the two antagonistic groups. Nova and Victor, despite their rivalry, develop an unexpected bond as they share visions indicating something supernatural is drawing them closer, hinting at a greater cosmic force at play.
The mysterious energy surges persist, posing a danger that extends beyond humans, threatening to harm zombies and werewolves in the area. As the Daywalkers and Vampires start working together to unlock the orchard gate, they face opposition from their elders, who are appalled to witness the unity. Their anger results in a tragic accident, burning half the orchard and deepening the division between the two groups, who then threaten war.
Further investigation reveals that the dying Blood Fruit roots are causing the dangerous energy surges. Nova and Victor believe that uniting their respective moonstones could heal the roots and resolve the chaos. However, fears about the difficulty of bringing their groups together threaten to undo the fragile peace. In a heartfelt moment, Addison, despite her weakened state, and a determined Zed encourage Nova and Victor to make what seems impossible become reality.
In the climax, the two groups unite their moonstones, successfully healing the Blood Fruit roots. This act stops the energy surges and causes a miraculous growth of Blood Fruit, symbolizing hope and renewal. The monsters celebrate their hard-won victory, but the elders, witnessing the newfound cooperation, react with hostility, threatening conflict once again. The groups part ways, still wary of each other’s intentions.
In the aftermath, Zed, Eliza, and Willa learn that the energy surges were caused by the dying Blood Fruit roots. The united efforts of Nova and Victor to bring their moonstones together demonstrate the tremendous power of cooperation, ultimately saving their ecosystem. As they watch the flourishing Blood Fruit, the characters reflect on their experiences and decide to cherish their relationships more than personal achievements, valuing the bonds they've formed. Nova and Victor agree to stay in touch, and just before they depart, a supernatural water spout forms over the ocean, hinting at future mysteries and adventures yet to come.
