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The Sequence is the tenth campaign main mission in Halo Infinite, under the fifth campaign section "Reformation". It is a multi-stage mission, which features four Forerunner energy beacons as the main objective.
The Sequence is the last story mission before the point of no return. When the player begins Nexus, they will cross this point and won't be able to attempt side missions until they complete the main story.
The Chief boards Echo 216.
The Chief steps inside the Pelican.
The Pelican begins to lift off. The Chief stands next to the troop bay's opening and stares out the open door while holding onto a side rail with one hand.
The Chief opens his free hand, allowing the Weapon's avatar to materialize on it. For a moment, she just silently stares out the Pelican's door as it flies over the Ring. She glances at the Chief, then looks away, hesitant to ask her question. Finally, she looks up at him again and asks her question.
The Chief turns and looks down at her.
The Chief hesitates for a few seconds before answering.
Scene slowly rotates around them.
She places a hand to her chest.
He trails off, clearly not comfortable talking about this.
The Chief doesn't reply. The Weapon's avatar disappears as the Pelican begins to descend.
The Chief turns to the troop bay's opening and prepares to disembark.
The Pelican reaches its destination.
The Chief jumps out of the Pelican and lands near the base of the Spire.
The Chief starts searching for the Command Spire's entrance. It doesn't take long for him to find a door.
If the Chief tries to access the door before dealing with the Banished guards:
After eliminating the Banished troops guarding the door, the Chief deploys the Weapon onto a nearby terminal.
Smiling confidently, her back to the door, the Weapon raises her hand and snaps her fingers. The Chief approaches the door, his weapon pointed at it. When nothing happens, he lowers his weapon and turns to her.
She turns to face the door directly and snaps her fingers three more times. The door remains locked. Defeated, the Weapon turns back to the Chief.
There's a rumbling sound from nearby. They look up to see a beam of blue energy - just like the one they and the Pilot saw back at the ship graveyard - shoot out from a Forerunner structure residing on a cliff.
The Chief uploads her back into his armor.
A pair of Banished Banshees descend upon the Chief.
The Chief destroys and/or hijacks the Banshees and moves on towards one of the Beacons.
The Chief approaches one of the Beacons.
The Chief eliminates all the Banished guarding the Beacon.
The Chief uses a terminal to open the Beacon's door.
The Chief enters the Beacon and, after a quick search, locates the chamber that houses the Beacon's Beam emitter. The room is bathed in a bright blue light from a continuous stream of data. He deploys the Weapon onto a terminal.
The Weapon stretches her arms in preparation.
She reaches out with one hand and extracts some data.
She tries extracting more data.
He retrieves the Weapon.
The Chief exits the first beacon.
The Chief doesn't answer.
The Chief goes to another Beacon and clears out the Banished guarding it.
He unlocks the Beacon's door.
The Chief enters the Beacon and locates the Beam emitter. As before, he deploys the Weapon onto the terminal.
She pulls some more data from the surrounding data stream.
She turns to the Chief.
She looks back at the data stream with an inquisitive expression.
Concerned, the Chief looks around the room. Seeing nothing, he retrieves the Weapon.
The Chief exits the Beacon.
The Chief reaches the third Beacon and kills all the Banished around it.
The Chief accesses to the door's terminal.
The door unlocks.
The Chief enters the Beacon, finds the terminal for the Beam emitter and deploys the Weapon.
She starts pulling data.
She suddenly finds herself struggling to pull the last bit of data.
The piece of data she's trying to grab suddenly pulsates with an ominous yellow light. The Weapon drops onto her hands and knees.
The Chief steps forward, his weapon raised. He searches for whatever attacked the Weapon.
Finding nothing, he lowers his weapon.
The Chief steps closer to her.
The Weapon gets back on her feet.
The Chief retrieves her.
The Chief exits the third Beacon.
The Chief approaches the final Beacon.
The Chief defeats the Banished guarding the Beacon and unlocks the door.
The Chief enters the Beacon.
The Chief locates the Beacon's terminal and deploys the Weapon.
She reaches out to extract some data, but suddenly pulls her hand back in alarm.
The Chief contemplates their next move.
The Weapon gives him a reluctant look.
Hearing this, the Weapon smiles. She turns around and goes to work.
The Chief's VISR activates.
VISR . OS \> COUNTERMEASURE ONLINE ACTIVATED DELETION PROTOCOL ... VISR . OS \> ISOLATING AI REQUIRED PASS PHRASE
RED FLAG ... ACCEPTED ... VISR . OS \> FAILSAFE PROTOCOL VISR . OS \> PASSCODE REQUEST REQUIRED PASSCODE
The VISR deactivates.
The Weapon finishes her work. She turns to the Chief.
The Chief takes a moment to respond.
The Chief retrieves her.
The Chief exits the Beacon and returns to the Command Spire. Banished troops have refortified the entrance and retracted the bridge needed to reach the Spire. A pair of Mgalekgolo arrive via drop pods. The Chief eventually kills all the Banished, locates the bridge controls, and extends the bridge. (Alternatively, he can just use a Banshee or Wasp to fly over to the Spire)
A Banished Phantom arrives and drops off additional enemy reinforcements led by a Sangheili Ultra. The Banished troops make a last ditch effort to stop the Chief from entering the Command Spire, but he defeats them all.
The Chief returns to the Command Spire's entrance and accesses the terminal for the door. This time the door unlocks and opens.
The Chief enters the Command Spire.
The following achievements can be unlocked on The Sequence across the all editions of Halo Infinite.