The beginning of the movie can focus on Dwayne Johnson/John Stewart's life as an architect in Detroit. Early on, it's established that John Stewart used to be a marine, we flashback to a scene where all of the members of his platoon are blown up by an IED. It's established that John Stewart feels guilty about being the only survivor of his platoon. Even though he's a gifted architect, he feels uncomfortable in his new position. He's finally able to overcome the demons that haunt him from his days as a marine once he puts the ring on. It is through becoming a Green Lantern that his life finds meaning again.
John receives the ring, experiments with it for a few quick fun scenes, and then he's rapidly transported to Oa. When he arrives on Oa, his arrival is met with hostility, and there is no immediate explanation for his arrival. Tomar-Re meets with John Stewart and informs him that the Guardians did not choose him to be a Green Lantern, and they speculate that the ring has come to John Stewart without the Guardians consent or knowledge. It is particularly unusual because Sector 2814 already has a Green Lantern. Hal Jordan. Hal was trained by Sinestro and they are best friends and partners. Hal feels threatened by John Stewart because he's cocky and thinks he can handle his sector on his own, and since it's unprecedented for one sector to require two Green Lanterns, Hal feels slightly embarrassed, so he doesn't give John Stewart an easy time. Sinestro is shown to be suspicious of John Stewart. He believes the Guardians are lying and chose John in secret..
At first, Tomar- Re is the only one to treat John Stewart with any respect. After his initial arrival and quick meeting with Sinestro and Hal, John is escorted by Tomar to meet with the Guardians. They are weary of letting John keep the ring, but Ganthet is able to convince the others to let John keep the ring. John at this point doesn't really have any idea what's going on, but decides to stick around since he doesn't really want to go back to his other life. During a discussion with Tomar-Re about what it means to be a Green Lantern, John is able to notice some similarities between the marine corps and the Green Lantern corps. Also during this conversation, Tomar tells John that he thinks John was chosen for a reason. He doesn't elaborate any further, before he tells John that he'll be doing combat training with Kilowog. Meanwhile, Sinestro is trying to convince Hal to go on a secret mission with him. Hal and Sinestro are shown to have a close relationship, it's clear they've been partners for a while so Hal agrees to keep the mission a secret from the Guardians.
Sinestro tells Hal that they are going to planet Ysmault to interrogate a creature known as Atrocitus. On their flight to Ysmault, Sinestro confides in Hal Jordan that he overheard the Guardians talking about a prophecy called "Blackest Night". He also thinks that John being chosen as a Green Lantern is related to the prophecy. On his own, Sinestro had done some digging to find out more and discovered that the Guardians imprisoned a creature known as Atrocitus on planet Ysmault. And this creature knows about the prophecy.
The planet Ysmault is a great opportunity to have some beautiful visual effects. Hopefully a reboot can have more visually appealing space scenes.
So they arrive on Ysmault and they discover the Atrocitus' prison. Sinestro initiates the interrogation and initially, Atrocitus tells him nothing, only expressing his hatred for the Green Lantern corps and the Guardians. Sinestro gets progressively more violent in his interrogation until Atrocitus is close to death. Hal intervenes just in time, and Sinestro lets up. Bloodied, Atrocitus just laughs and basically tells them that there will be a war between all the different colored lanterns. Sinestro's gotten the information he needs so him and Hal decide to leave. Sinestro verbally attacks Hal for making him look weak in front of Atrocitus. He argues that the situation calls for serious measures to be taken.
The Atrocitus interrogation is intercut with scenes where Kilowog is basically kicking John Stewart's ass/"training" John until Kilowog gets John angry. John shows an abnormal amount of will and knocks Kilowog on his ass. Kilowog is stupefied, its the first time someone has done that to him in their first training session.
After Kilowog's training session, Tomar- Re tries to teach John to make complicated constructs, but with his job as an architect, it's already easy for him to do, and the more complicated constructs come naturally. Hal and Sinestro arrive around the same time that Tomar Re decides he couldn't even really teach John anything. John asks about both Hal and Sinestro. It is here where we get brief origin explanations for both of these characters. A brief gloss over of Hal's origin and Sinestro's origin (with emphasis on the fact that he frequently disagrees with the Guardians and is known for a wicked temper and his willingness to get violent when deemed necessary) it's established that Hal Jordan and Thaal Sinestro are generally regarded as the best Green Lanterns.
As soon as Hal and Sinestro arrive on Oa, they go straight to the Guardians to confront them about the prophecy. The guardians unanimously deny knowledge of any prophecy, but Ganthet and Scar both act suspiciously (its clear they both know full well what's going on).
Sinestro is furious that the Guardians would lie to him. Sinestro angrily asks Hal Jordan to leave so he can speak with the Guardians alone.
Hal leaves and notices John Stewart talking with Tomar and decides to approach him. Hal is initially somewhat hostile but he says things in a joking manner to make himself feel okay about being a *****e. John shouldn't have a high threshold for disrespect, so he'll reciprocate the hostility.
Sinestro, alone with the guardians, pleads with them to let him forge a yellow power ring in order to combat what he knows is coming. He suggests that the yellow element is more powerful, and would be more effective, but the guardians deny this. They prohibit Sinestro from forging a yellow ring and discourage him from even speaking about it. They suggest that the energy that powers the yellow element is too uncontrollable and unpredictable. They also keep up the lie and deny any knowledge of a prophecy, further infuriating Sinestro. In an effort to change the subject, they inform Sinestro of a mysterious distress signal in Hal Jordan's sector. They suggest that Hal and Sinestro investigate the disturbance. Sinestro suggests that John and Hal investigate it together. Sinestro furiously leaves the guardians and Oa without speaking a word.
The Guardians inform Hal and John of the mystery distress signal, and Hal begrudgingly agrees to take John along. They travel for a while until they arrive on the planet where the signal was coming from. The source of the distress signal is apparently within a seedy space bar. We see here how the sight of a Green Lantern costume strikes fear into the hearts of seedy looking space criminals.
They ask around trying to find out who activated the distress signal, but no one knows. A hooded woman with skin the same color as Sinestro's sits at a table nearby, eying them from the corner Aragorn in Fellowship of the Ring style . John, clearly intrigued by her otherworldly beauty decides to approach her. She explains that she is Katma Tui of Korugar and that she activated the distress signal. The distress signal was given to her by her late father, who had received a device after saving the life of the deceased Green Lantern, Abin Sur. The device somehow notifies the Green Lantern corps if trouble is afoot. When asked why she is all the way in sector 2814 if she is from Korugar, she responds that she needed to go somewhere as far away from Korugar as possible in order to feel safe activating the device. She apologizes for not approaching them immediately, but wanted to make sure that Thaal Sinestro wasn't with them. Before she can tell them why, we cut back to Sinestro.
After abruptly leaving Oa after his heated conversation with the Guardians, Sinestro has returned to his home planet, Korugar. It is revealed that he has already forged a ring using the yellow element. He has forged multiple rings in fact. Korugar is ruled with an iron fist by the element of fear. Sinestro has already assembled an army on Korugar, powered by the yellow element. Arkillo, Sinestro's right hand man is in charge when Sinestro is on Oa. I say in this introduction scene to the way life is on Korugar, we should get a scene to establish how ruthless Arkillo is. Perhaps a thief is brought to Arkillo, and the man cries and falls to his knees in front of him begging for his life. Arkillo creates a yellow blade and cuts the thief's hands off, and the thief is escorted away.
Sinestro then tells Arkillo that there is no hope for the Guardians. That they will only get in the way of his plan. He explains that their lies created a rift that can't be repaired, and that their plans must be hastened. He plans an assault on Oa. He's planning this because he knows that the Yellow Lantern corps won't be allowed to exist as long as the Green Lantern corps exists. He also intends to forcefully extract information from the Guardians regarding the prophecy. His plan is for the Yellow Lantern corps to be the ruling force of the galaxy, he wants his corps to protect the universe from the prophecy, and the Green Lanterns will only get in the way as long as they exist. Before the assault however, he intends to return to Oa in an effort to convert Hal.
Back to Hal, John and Katma...Katma reveals to John and Hal how Sinestro is ruling Korugar. Katma was the leader of a rebellion against Sinestro and eventually was forced to leave Korugar for her own safety. Her entire family was heavily involved in upper level positions in the rebellion, but they were all wiped out. Katma was the only one able to escape, and she hitchhiked across the galaxy, downplaying her identity and beauty in an effort to stay hidden. As soon as she felt safe enough she activated the distress signal. John is clearly enamored by this woman and believes what she's saying, but it's clear that Hal isn't so sure of her. He's not so ready to believe that his partner and best friend would be capable of such things, but then he remembers how he acted against Atrocitus and once again isn't so sure what to think. They assure Katma that they will look into it, and ask her if she needs a lift anywhere, she declines, feeling safe in the seedy space bar.
Hal decides that they should stop at Oa first to see if Sinestro is there. Hal wants to confront Sinestro himself first. When Hal and John arrive, Sinestro is already back on Oa, as he is ready to make an attempt to convert Hal Jordan. Hal and John confront Sinestro about the things Katma told them, and it's clear Hal is really conflicted here. Sinestro is able to somewhat convince Hal that John and Katma are working with the Guardians to keep things from Hal. Sinestro tries to convince Hal that the yellow energy is necessary, and plays on the fact that the Guardians have lied to Hal before about the prophecy, and are working against Hal and Sinestro. Hal is eventually able to come to his senses and rejects Sinestro's offer to join him. Sinestro is sad about what he has to do, but he drops his Green Lantern ring and puts on his Yellow Lantern ring and calls in the assault on Oa.
The GL's are shown to be utterly unprepared, and there are hundreds of casualties. We need to get a quick Sinestro/Hal fight sequence, where Sinestro tells Hal how they could have ruled the universe with Hal at his side. We then follow the GL ring that Sinestro dropped , and we see it approaching a familiar planet.. the planet Katma is staying on. She receives the GL ring and before she has any time to learn to use it, she's transported to Oa...into a battlezone. When she first arrives, she's caught off guard and ambushed by multiple Yellow Lanterns. John swoops in and saves her and gives her a quick tutorial on how to use the ring. She proves to be a natural though. She's able to positively channel her emotions about Korugar into more power from the ring.
There should be a scene where Arkillo and Kilowog are fighting each other. We cut to the Guardians all retreating to an underground cave where they keep the central power battery. Protecting the central power battery is crucial. John and Hal realize that the only way to win the battle is to take out the central yellow battery. Luckily, Katma can show them exactly where it is on Korugar. Hal, John, and Katma race back to Korugar after the battery. Once they arrive, they face off against a large number of Sinestro Corps members, but eventually dispatch them. Katma leads Hal and John to the central battery.
The green element is the only weakness of the yellow element so with enough willpower and concentration, the 3 Green Lanterns are able to crack open the yellow battery just enough for the energy to start seeping out. At this time, an infuriated Sinesto arrives and unleashes a vicious attack on the three of them. His rage makes him powerful enough to take on the three of them at once. The energy seeping out of the battery appears to be sucked into Sinestro's ring, powering him even more. John and Katma decide to continue their attempt to break open the battery, while Hal holds off Sinestro. Eventually Sinestro gains the upper hand and is about to kill Hal when John swoops in and saves Hal. It's here that we finally see both Hal and John respecting each other. Hal and John take down Sinestro together, and then focus their efforts on the Yellow battery. but the battle isn't over... the fight is still raging on Oa.
Hal, with the help of Katma and John is able to fully crack open the yellow battery, but as soon as he does, there is a massive flash of bright yellow light, and we get a quick half second look at an enormous yellow monster emerging from the battery and entering Hal's body. Hal screams like someone would if the essence of fear were entering their body, his temples grey, and he's then weirdly calm. John and Katma believe they have saved the day, and try to brush off Hal's weirdness after breaking open the power battery.
They return to Oa to find the depowered Sinestro corps defeated. The Guardians soon gather around Hal, John and Katma and ask them how the lantern rings were depowered.. John and Katma tell the guardians that they broke open the yellow battery. The normally emotionless guardians appear to be terrified as soon as they found out the battery had been broken.
Hal begins to laugh maniacally and Parallax begins speaking through him. He eventually leaves Hal's body and returns to the monstrous yellow form that we saw before it entered Hal. Hal's body drops to the floor, apparently dead.
So now a giant yellow monster that is literally the embodiment of fear is unleashed on Oa. Eventually with the help of the guardians, John, Katma, and the remaining Green Lanterns, the monster is able to be contained.
After Parallax is defeated, Hal wakes up and he and John shake hands, and of course, John and Katma kiss. It is also revealed that Ganthet secretly sent the Green Lantern ring for John Stewart. He had a vision that John Stewart would be a major part of the prophecy. He reveals that John Stewart's role in the prophecy is yet to be revealed, and that his help in defeating the Yellow Lanterns and Parallax was merely a bonus, unrelated to the prophecy. I'd end the movie with John deciding not to return to Earth, but to keep working alongside Hal and Katma. This is the first time he's felt like his life has had any meaning in a while. He sees Hal and Katma and the other Green Lanterns like members of his platoon now.
