In the year 2557, after the defeat of the Didact, UNSC Infinity returns to Requiem to investigate the Forerunner Planet. There were a bunch of Spartan-IV Fireteams on UNSC Infinity, but the main two are Fireteams Crimson and Majestic. Fireteam Crimson is a four man squad and their squad leader is Spartan John Walker. Walker has been the UNSC's Top Spartan-IV, but his inspiration to join the Spartan-IV Program was because of the Master Chief, Humanity's Greatest Hero. During the Requiem Campaign, Walker and his squad did a lot of amazing things, even surviving the first encounter with the Prometheans, from what he read of the report. They recovered an Artifact that basically acted as a teleporter down to the planet. Walker and the rest of Fireteam Crimson were sent down to Requiem to hunt down Parg Vol, a Sangheili Terrorist and known associate of the Covenant Leader, Jul'Mdama. Although, he might've evaded their first and second hit, they found and killed the Sangheili Terrorist.

Walker and his Team were back on Infinity to prepare for their next mission until Commander Sarah Palmer walked in and said,

"Spartan Walker, The eggheads have something for you."

Walker followed the Commander to the labs where the scientists were finishing up on a new MJOLNIR Powered Assault Armor. The Scientists noticed the Spartans as the head Scientist asked the Commander,

"Is this the Spartan that the Captain wanted?"

Palmer replied, "Walker happens to be one of the best Spartans on this ship. Captain Lasky requested that Walker tried out this experiment." Walker noticed a little sarcasm in her voice. Walker always knew that Commander Palmer never liked scientists, but they designed the armor, but in truth it was Dr. Halsey who designed it, but she was a scientist. When he knew that Halsey was onboard Infinity, he wanted to go speak with her about her…..methods for creating the Spartan-IIs like the Master Chief, but he had other matters that he had to deal with. The head Scientist asked Walker,

"Spartan Walker, you want to know why you are here."

Walker replied, "I was requested to come down here, because you have a new experimental armor."

The Scientist introduced the new armor, "This is the Prefect Armor, and it was first tested Denegroth on Europa. The Prefect Armor is a hybrid of Human and Forerunner technology from the Shield World which was formerly known as Onyx. Infinity received the schematics for the armor, and we build a set of the armor on this ship. But we needed a Spartan and the Captain requested you to use the Prefect Armor."

Walker finished, "And you want me to use it in combat on Requiem?" The Scientist nodded as Walker stepped into armor assembly systems as he was rotated around while the mechanisms place the pieces of the Prefect Armor on his undersuit. When he stopped rotating and he was wearing the Prefect Helmet, he looked at the armor that he was wearing and looked the pointy armored feet and said,

"This armor is pretty interesting."

The Scientist replied, "Don't mind about the helmet's visor. It still produces a traditional HUD like in the other helmets."

Commander Palmer complemented, "You look good, Walker." The Prefect Spartan replied, "Likewise, Ma'am."

Walker and Fireteam Crimson were sent down to Requiem to find Gabriel Thorne of Fireteam Majestic. But while they were waiting for extraction, their evac pelican was shot down and they were captured by the Covenant. Walker put the Prefect armor to good use when he and his team broke out and captured a Phantom along with Lieutenant TJ Murphy who became their pilot. After going on a bunch of incursions using the captured Phantom, Walker and his team discovered a bunch of HAVOK mines missing their warheads. Soon after that, they were recalled to return to Infinity to hold off a Storm Covenant Attack on the ship. After holding off the attack, Walker overheard a conversation between Captain Lasky and the bitch herself, Serin Osman. He read Osman's background and discovered that she was a Spartan-II Washout for failing the augmentations. Walker thought to himself,

"No wonder she hates Dr. Halsey." That name soon struck him when he realized that she was abducted by the Prometheans. After listening in on the conversation, Walker was shaking in his Prefect Armor to warn Fireteam Majestic.

Once he reached Fireteam Majestic, he explained what he heard during the conversation about Osman giving Lasky the order to eliminate Catherine Halsey. Majestic just listened to him and studied every single bit of information that Walker gave them. Spartan DeMarco asked,

"Are you sure that Admiral Osman gave a kill order on Dr. Halsey?"

Walker nodded, "I'm real sure about it. If the Master Chief got word of Admiral Osman ordering a kill on Halsey…..well, he might just have to kill Osman."

Spartan Grant asked, "So why did you come to us when you could've explained it to your fireteam?"

Walker shrugged, "Fireteam Crimson is already preparing for another mission down to Requiem. But I have an assignment for you, Majestic."

Spartan Thorne who just got back to Infinity asked, "What do you want us to do?"

Walker took out the kill order, "It's most likely that Commander Palmer would carry out killing Halsey. I want you guys to follow Commander Palmer, stop her and rescue Halsey from Jul' Mdama."

Spartan Anthony Madsen asked, "Why are you doing this?"

Walker replied before leaving, "I think that she helped Jul'Mdama because he had no knowledge of Forerunners choosing humans over his own race. But Glassman told me that Jul is after the area where the Chief encountered the Librarian. Jul is as blind as the loyalists were during the war."

Walker and his team went through their mission and rescued Fireteam Switchback which was captured by the Covenant in an attempt to disable a Covenant Harvester. After going through their missions, Walker and his team were now set on an emergency broadcast as Captain Lasky warned,

"All Spartan Teams, this is Captain Lasky. We have an emergency!"

Walker said, "This is Crimson, go ahead sir."

Lasky responded, "Jul'Mdama got away with Halsey and Requiem is on a collision course with the sun."

Walker said, "Roger, We're going to evacuate Requiem."

Commander Palmer butted over the comm, "Negative, Crimson! Infinity is anchored to Requiem by two artifacts that are in separate locations. Majestic and I are going after the one on our end."

Walker nodded, "My team will go after the other."

"Just don't let the Covenant kill you before I do for ordering Majestic to stop me behind my back." replied Palmer.

Walker shook his head to know that Palmer found out, so he ordered Crimson to return to the Harvester, only to discover that it's been disabled and it needs a new power core. Crimson went into another area where Crimson 2 salvaged a Power Core from a Covenant Lich. They returned to the Harvester, where Crimson 3 powered up the Harvester and destroyed an obstruction in their path. Crimson 4 took point while Walker took the rear and kept an eye out for Prometheans. When Crimson reached the artifact, they took what much time they had left, disabling and retrieving the artifact. Walker and his team loaded the artifact onto the Pelican and contacted Majestic,

"Crimson to Majestic, Status Report!"

Commander Palmer came on, "Walker, you disabled the artifact yet?"

Walker replied, "Yeah, we did…" He heard gunshots from both sides as both Covenant and Prometheans began firing on him. He also heard some gunshots on Palmer's end, he said as he ran for the Pelican,

"MOVE IT, MAJESTIC!"

He boarded the Pelican and was ready to be off of Requiem for good.

Lasky heard from Roland, the Ship's AI, that both Crimson and Majestic were on their way back to Infinity and time was nearly out as Requiem was dangerously close to the sun. Roland said,

"Sir, Crimson and Majestic are inbound for Infinity."

Lasky nodded, "Nice Job, let's hope they can get aboard." He heard a transmission between the two Pelicans. One was Walker's voice,

"Commander Palmer, That artifact we've loaded onto the Pelican is showing some activity that is different from the one we recovered before."

Palmer replied with sarcasm, "What seems to be the problem, John?"

Walker replied, "Sarah, its….its linking itself with my armor!" Crimson's Pelican vanishes into a Slipspace Rupture as Palmer yells,

"Crimson, come in. Crimson….Walker, are you there!?"

Thorne watched as the rupture disappeared, "Commander, we'll worry about them later, we need to get back to Infinity."

Majestic's Pelican reached Infinity as the ship entered a Slipspace when the artifact onboard Infinity tampered with the Ship's Forerunner engines therefore causing Roland to detect a Slipspace anomaly. As Palmer and Fireteam Majestic exited the Pelican, Palmer told DeMarco,

"Walker told you guys to stop me."

Spartan Grant responded, "Because unlike you, he doesn't trust Admiral Osman and judging by her history with Halsey, it was with good reason."

Spartan Thorne took out the first half of the Janus Key, "If Halsey was in line with Jul'Mdama, why would she give us this?"

Meanwhile on the Covenant's side, Jul'Mdama was furious about Halsey giving one half of the Janus Key to the Spartans as well as losing her arm, he said in human language,

"You've given the other half to your compatriots?"

Halsey replied, "Only to find out that my 'Compatriots' were a Firing Squad. But one managed to fire while the others did not."

Jul asked, "How come the others didn't kill you?"

Halsey smiled, "Spartan Commander John Walker, the only Spartan wearing the Prefect Armor. I suppose your men have reports of him and his team?"

The Shipmaster looked at the various reports of Fireteam Crimson and saw the Spartan that she was talking about. "This is this John Walker?"

Halsey nodded, "He is the UNSC's Top Spartan-IV all those commendations he earned in the past 4 years were because of his faith in my Spartan, John-117."

Jul sneered, "You created the Demons?"

Halsey calmly responded, "Now is not the time to talk about what I did."

Jul let it go for now and asked, "What do you propose?"

Halsey took the Janus Key and said, "The UNSC tried to execute me and I know who's responsible."

Jul asked, "What do you wish?"

Halsey replied, "Its simple, Jul. I want revenge on Admiral Serin Osman."