Johannes is a free-roaming dog born in a park by the sea working as the vigilant "Eyes" for the ancient bison rulers—Freya, Meredith, and Samuel—who maintain the park's equilibrium. Despite his domesticated mother's care, Johannes was raised in the wild with his siblings Joanie, Janie, and Steven, who were later taken by humans. Johannes observes and reports all activities from harmless visitors to disruptive groups like the Concerteers and Trouble Travelers.
His life changes after a night under a star-filled sky when he meets the Assistant Eyes—Bertrand the seagull, Sonja the one-eyed squirrel, Yolanda the clumsy pelican, and Angus the nocturnal raccoon. Together, they help Johannes monitor the park and report to the ancient bison rulers.
One Sunday, while avoiding uniformed humans and helpers, Johannes notices an intriguing new display of colorful rectangles in the park's plaza. One rectangle captivates him with its surreal depiction of a serene child amidst chaos. A human child touching him while he admires an intriguing rectangle in the park startles Johannes. The child starts crying, which draws adult attention and forces Johannes to flee. He shares only part of his day's experiences with the Bison, omitting the touch. The next day, Johannes returns to the park, mesmerized again by the surreal rectangle. Distracted, he is unexpectedly leashed by a young man identified as Twisty.
Twisty drags him to a vehicle filled with other unsavory characters, including Pamela and Rainbow. They plan to use Johannes in their thefts. Inside the dark and smelly vehicle, Johannes hopes to signal other park animals for help. As the vehicle approaches the city, Johannes despairs because he is unable to find an escape. However, when Twisty turns him on his back, Johannes sees a window in the roof, which reignites his hope for rescue. Bertrand, Yolanda, and Sonja the squirrel come to the rescue. Sonja bites through his leash and jumps out of the van. Johannes follows Sonja back to the safety of the park where he celebrates his rescue with his friends. Later, Johannes worries about reporting his abduction to the Bison, but they reassure him of his safety.
Disguised in a sweater, he embarks on a risky mission with Bertrand's aerial support to blend in with humans and their kept dogs. Despite his ability to run at incredible speeds, he becomes mesmerized by the chaotic paintings displayed on the building's exterior. As he navigates the bustling crowd, he narrowly avoids capture by Control-the-Animals personnel. Bertrand suggests a plan to explore the building when it is empty to satisfy his curiosity about the mysterious rectangles.
Johannes learns from the goats and Freya that their island is a small replica of a much larger world beyond. Feeling troubled and alone, he wanders to the edge of the park while contemplating the vastness beyond. The next day he encounters signs warning of a coyote in the park. Though he engages with strange animals like Helene the goat, he still feels the weight of his responsibility. Johannes rushes to find Bertrand, eager to share both troubling and happy news. Unable to locate Bertrand at first, Johannes eventually discovers him injured on the archery field. They work together to help Bertrand remove the arrow and comfort him. They then proceed with their plan to liberate the Bison as they rely on Angus and his team of raccoons for assistance. Finally, they find a boat that they can board with the goats for the unknown expanse of the sea.
