In a city park, Surly, a self-serving but mischievous squirrel, is banished by his fellow animals because of a disaster during a nut heist that he inadvertently caused. The accident leaves the park's wildlife community with a depleted food supply for the winter, increasing the animosity against Surly. Stubborn and solitary, Surly is forced to survive on his own in the big city. He soon discovers Maury's Nut Shop and hatches a plan to plunder its bounty, which would provide him with more than enough food to get through the winter.

Meanwhile, the park's furry residents, led by Raccoon, the self-proclaimed leader, and Andie, a compassionate and hard-working red squirrel, are struggling to find a new food source. When Surly's paths cross with Andie, they reluctantly partner up. As they embark on the heist at Maury's Nut Shop, they also deal with precariously aligned interests: Surly's desire for self-preservation clashes with the park community's need to stock up for winter. But they aren't the only ones aiming for the nut cache—human thieves have also targeted the shop for their own criminal ends.