Millions of years before Earth came into existence, a powerful group known as the Guardians of the Universe utilized the green essence of willpower to establish an intergalactic law enforcement agency: the Green Lantern Corps. This organization divided the cosmos into 3,600 sectors, assigning one Green Lantern to each sector. Among them was Abin Sur (played by Temuera Morrison), who valiantly confronted the fear-essenced entity known as Parallax (voiced by Clancy Brown) and successfully imprisoned him in the Lost Sector on the desolate planet Ryut. However, in today's world, Parallax breaks free from his confinement.
Following six months of chaos that saw the destruction of two planets and the deaths of four Green Lanterns, Parallax's terror extends to Sector 2814, where he fatally injures Abin Sur. In a desperate flight, Sur crash-lands on Earth, using his dying breath to command his ring to seek out a worthy successor.
Enter Hal Jordan, a talented test pilot for Ferris Aircraft, portrayed by Ryan Reynolds. Hal faces both personal and professional turmoil as he loses his job after outmaneuvering state-of-the-art UAV Sabers with a conventional F35, costing his company a lucrative Air Force contract. Haunted by the memory of his late father—also a test pilot who perished in a tragic accident—Jordan struggles with the weight of his past. His girlfriend, Carol Ferris (Blake Lively), who co-owns the company and shares his passion for flying, watches with disappointment as Hal spirals into despair.
Summoned by the ring, Hal finds himself at the crash site where Abin Sur bequeaths him the title of Green Lantern, instructing him to take the lantern and recite the oath. Just as government aircraft arrive, Hal barely escapes, and back home, entranced by the lantern's aura, he solemnly recites the Green Lantern oath. His life takes an unexpected turn when he retaliates against muggers, unleashing a colossal fist of green energy, igniting his new powers.
Transported to Oa, the home of the Green Lantern Corps, Hal trains alongside Tomar-Re (voiced by Geoffrey Rush) and Kilowog (voiced by Michael Clarke Duncan), and encounters the Corps' leader, Sinestro (Mark Strong). Sinestro, perceiving Hal as inferior due to his humanity, questions his worthiness. Feeling unaccepted, Hal decides to abandon his role and return to Earth, maintaining possession of the ring and lantern.
Meanwhile, Hector Hammond (Peter Sarsgaard), a scientist and son of Senator Robert Hammond ([Tim Robbins]), conducts an autopsy on Abin Sur's remains at a secret government facility. In a twist of fate, a fragment of Parallax embeds itself within Hector, granting him telekinesis and telepathy while unraveling his sanity. Fueled by resentment for being overlooked, Hector attempts to murder his father by sabotaging his helicopter during a public event. Jordan intervenes, rescuing the senator and Carol, who recognizes Hal beneath the Green Lantern disguise. Yet, tragedy strikes as Hector finally succeeds in executing his father.
As the threat of Parallax looms large over Earth, Hal's journey leads him back to Oa, where the Guardians reveal Parallax's tragic transformation from a Guardian into a being of fear. Sinestro, convinced that fear must be met with fear, seeks the creation of a yellow power ring, intending to relinquish Earth to Parallax to safeguard Oa. However, Hal stands against this decision, rallying for the Corps' support in defending his home. Despite initial rejection, they permit Hal to return to protect Earth.
Reinforced by determination, Hal saves Carol from being consumed by Parallax's essence, only for the entity to consume Hector for his failure. In a climactic showdown, Hal lures Parallax toward the Sun, utilizing its immense gravity to obliterate the monstrous being. Though he loses consciousness post-battle, he is rescued by Sinestro, Kilowog, and Tomar-Re, later earning accolades from the Green Lantern Corps for his valor. Sinestro, however, intrigued by the power of the yellow ring, places it on his finger, transforming his green suit into a foreboding yellow, hinting at darker challenges ahead.
