'The Last of Us' Finale Delivers Treat for Game Fans, and Answers a Mystery

Following a record-breaking nine-episode run, HBO's The Last of Us ended its debut season Sunday night. The hit series has chronicled the journeys of Pedro Pascal's Joel and Bella Ramsey's Ellie in a post-apocalyptic world 20 years after modern civilization has been destroyed by a mass fungal infection caused by a mutation in the genus Cordyceps. Warning: This post contains spoilers for The Last of Us Season 1, Episode 9, "Look for the Light."

Based on the Naughty Dog video game of the same name, The Last of Us has been praised by fans and critics alike as the best video game adaptation ever made, with one moment from the Season 1 finale being pulled directly from the game. As Joel and Ellie narrow in on the Fireflies, completely unbeknownst to them,they stumble upon a free-roaming giraffe in Salt Lake City while cutting through a building. The sight prompts genuine joy and laughter from Ellie for the first time since their run-in with Pastor David (Scott Shepard) in Episode 8, and the sight of a herd of giraffes stands in stark contrast to the bombed city and what remains of human civilization, the giraffes seem to be thriving, just as the monkey in Episode 6 had. The scene was a pivotal one in the game, with IGN even previously referring to it as "the most important moment in The Last of Us," and it was just as impactful in the TV adaptation, offering Joel and Ellie a rare moment of peace followings months of hardships and near-death experiences.

The season finale did stray away from its source material, though. While the game never explains Ellie's immunity, the final episode of the HBO series also offered the first explanation. Up to this point, Ellie's immunity – the very reason she and Joel have traveled across the country – has been a mystery. However, the opening minutes of The Last of Us Season 1 finale offered some clarity, revealing that Ellie's mother, Anna, was bitten by a Runner (the first stage of infection). The cold open showed Anna, portrayed by Ashley Johnson, who portrayed Ellie in both video games, seeking shelter in a home from a Runner just as her water breaks. Although she ultimately manages to kill the Runner once it breaks into the room, it is revealed she has been bitten, with Ellie's umbilical cord still attached. Later in the episode, it's explained that Ellie was likely born with the cordyceps already in her and the cordyceps has likely grown with her, making her immune.

Unfortunately, though, cordyceps grows in the brain, making her quest to help find a cure a lethal one for her. After finally reaching the Fireflies, it is revealed that their plan is to remove the cordyceps from her body to find a cure, a process that would ultimately kill her. Joel manages to save her from that fate, killing what remained of the Fireflies in Salt Lake City, and possibly the only hope for a cure, in the process.

The Last of Us Season 1 is available to stream on HBO Max. The series has already been renewed for a second season.