In Upper Paleolithic Europe, approximately 20,000 years ago, a small tribe of hunter-gatherers gears up for an important expedition to secure food for the upcoming winter. At the helm is Tau (Jóhannes Haukur Jóhannesson), the tribe’s chief, who has chosen his teenage son, Keda (Kodi Smit-McPhee), along with another boy, to join the hunting party. However, before they can embark, the young aspirants must prove their worth through various tasks, one crucial test being the crafting of a stone spearhead. Keda impresses everyone with the sharpness of his spearhead, marking the beginning of his initiation.
The initiation process involves a roughing-up by the rest of the hunters, which culminates in Tau gifting Keda his own necklace—a tangible symbol of acceptance. Tau emphasizes to Keda the critical necessity of hunting bison for the tribe’s survival during the harsh winter months. Meanwhile, Rho (Natassia Malthe), Keda's mother, expresses her concerns, fearing that her son may not be prepared for such a significant responsibility. Despite Rho's worries, Tau confidently assures that Keda will return a leader, capable of guiding the tribe.
However, Keda's journey is fraught with challenges as he struggles with his inexperience—he is unable to light his own fire at first. Tau reminds him to practice patience and learn vital skills necessary for survival. Their journey takes them along the Great Path, marked by grand stone monuments left by ancestors, which serve as navigational markers to the bison hunting grounds.
During the expedition, Tau puts Keda’s resolve to the test by having him kill a boar. Unfortunately, Keda falters, prompting Tau to express his frustration, insisting that Keda must learn to take life to sustain their tribe. One harrowing night, the hunters' fire attracts the attention of a dangerous Machairodus (a large cave lion), leading to a tragic event where Keda’s friend is snatched away, leaving the tribe in mourning.
The tribe honors their lost member with rituals, placing rocks to symbolize the journey of the spirit into the afterlife. They also possess knowledge of tattooing, which they utilize to engrave star maps on their skin, aiding hunters stranded far from home.
Late at night, Tau teaches Keda about the complexities of leadership within wolf packs. He explains how an Alpha must maintain the pack’s safety while also navigating challenges from competitors. An Alpha must earn respect rather than inherit it by virtue of birth.
Eventually, the hunters locate a herd of steppe bison and devise a plan to stampede them off a cliff. The situation quickly escalates when one bison veers off course, charging directly at Keda and causing him to fall from the cliff, leaving him injured and unconscious, hanging precariously between the rocky ledge and a treacherous ravine below.
Despite Tau’s desperate attempts to save him, with others convinced Keda is dead, the tribe departs, collecting the bison meat before conducting another funeral ritual. However, Keda is not dead. He regains consciousness thanks to a vulture mistaking him for deceased prey and kills the bird for sustenance. As a sudden downpour engulfs the ravine, Keda seizes the moment to escape his rocky prison and plunges into the flooding waters below, narrowly surviving.
Adapting to his new reality, Keda faces the wilderness alone, surviving on dirty water and worms. He soon encounters a pack of wolves, evading them by taking refuge in a tree after wounding one. Rather than slaying the injured wolf, Keda shows mercy, nurturing its wounds. This act of kindness forms an unexpected bond, and as danger looms from a pack of hyenas, Keda and the wolf find shelter in a cave where Keda successfully ignites a fire.
Over time, Keda builds trust with the wolf—whom he names Alpha—by feeding it first before himself, establishing a unique companionship. Their bond strengthens as they collaborate to hunt small boar. However, winter ushers in new challenges; on a frozen lake, Keda falls through the ice but is saved by Alpha, who bravely aids him.
Continuing their journey together, they come across a man who has succumbed to the cold, scavenging a bow and arrows from his remains. They face peril once more when a Machairodus attacks in a nearby cave. In the heat of the moment, Keda kills the beast but not without consequences—Alpha is left severely injured, and Keda starts to show signs of illness himself.
As Alpha struggles to move, Keda selflessly carries his wounded companion, refusing to abandon his friend. Eventually, Keda arrives back at the village and is joyfully reunited with his parents, who are filled with pride at their son’s resilience and courage. To Keda’s astonishment, Alpha gives birth to a litter of pups, leading to their official acceptance into the tribe. In time, the tribe evolves to include both humans and their newfound wolf companions, transforming their hunting endeavors into a collaborative effort between species.
