The newborn wolf pup, Wander, begins narrating his story from the safety of the den where he is born. Tenacious, curious, and energetic, Wander longs to venture outside but is forbidden to cross the scent line marked by his elders that declares, “DO NOT PASS.” Wander is known to his family as Swift because he is the first of his litter to stand and walk. His sister Pounce loves to wrestle with her siblings. His sister Wag uses her tail as her primary method of communication. Sharp, Wander’s larger, elder brother, is assertive and aggressive, and Wander already views him as a rival. Wander’s favorite sibling is Warm, his smaller, cuddly, submissive brother. Wander wrestles with his siblings for access to his mother’s milk and listens as his mother imparts wisdom essential to the young pups’ survival. One night, as Wander dares to creep past the line, an unfamiliar wolf appears, growling a warning to remain in the den. Wander knows from the wolf’s scent that he is also family. On the wind, the pups sense their mother approaching with the rest of the pack. Although Wander recognizes his father by scent, he is intimidated and cautious when approaching him for the first time.