Zero Hour

Zero Hour is a secret quest found on Earth when the player has the Fallen Transponder and has activated all 6 of its nodes. A completion of this quest awards the player with the Outbreak Perfected Exotic Pulse rifle. This quest can be accessed via the Earth directory or by interacting with Mithrax, the Forsaken in The Farm basement after the player has the Fallen Transponder and has activated all 6 of its nodes.

Heroic version
After the completion of the quest, a heroic version will be available via an option after selecting the Zero Hour mission on the Earth directory. When the player completes the heroic version of Zero Hour for the first time, they will be awarded the Outbreak Perfected Exotic catalyst. After the player completes the heroic version of Zero Hour for the first time, further completions will award 100 SIVA Nanites which count towards completing the Outbreak Perfected Exotic catalyst. The heroic version also allows the player to complete a Whisper-like secret challenge to obtain Ship Schematic Exotic Bounty. To complete this bounty, the player will need to complete the challenge on all 3 weekly singes (Void, Arc, Solar) which then awards the Scrap CF-717-91. One singe challenge also gives the player 67 SIVA Nanites, resulting in 3-week catalyst completion, if done in all singes.

Gameplay
The mission is similar to The Whisper in the way that players are given 20 minutes to complete it and that some enemies have Elemental Absorption shield on them. The mission starts at old tower (the place where Amanda Holliday rendezvous with the Guardian in Homecoming), which is overrun by Fallen. Players must clear all the enemies from each room before they can proceed forward. After clearing everything they must run through maze-like ventilation system and rooms with jumping puzzles. Some rooms have switches that can be activated to make the route easier for those behind. After awhile the players encounter a giant maze-type of room with 4 switches that must be activated in order to progress, guarded by TR3-VR (Trevor), a sweeper bot that stalks the corridors. Players must avoid TR3-VR and activate the switches to open the door at the back of the maze that leads to a small room with 4 elevators that will fall down right before they reach the upper level. After small fall and some running, the players encounter Siriks, Loyal to Eramis, the Fallen captain behind the attack. Players must kill Siriks and all other enemies before the time runs out. After everything is killed, Mithrax will teleport to the arena, signaling the success of the mission, and rewarding the fireteam with Outbreak Perfected Exotic Pulse Rifle, or the Catalyst if done in Heroic.

Obtaining the Fallen Transponder and activating the nodes
In order to start this quest, the player must complete Enemy Of My Enemy on Titan. After completing this World Quest, proceed to The Rig and travel south towards the Tidal Anchor. Continue through the hallways until you reach a red room with two closed doors. The left side door has a prompt that reads "Unlocked". Interact with the door then proceed through the room and there will be a red node right next to a table, interact with the node and the player will obtain the Fallen Transponder. The Fallen Transponder requires the player to collect six nodes in order to make progress. Four of the nodes are located on Earth and the other 2 nodes are located on Nessus. All of the nodes will be in lost sectors. After collecting all the nodes, go to The Farm and take a right from the spawn point toward a cellar right next to the hangar and go down the stairs, at the very bottom, Mithrax, the Forsaken will be crouched down at the end of a hallway, and then the actual quest will begin.

Trivia

 * The path players take through the beginning of the mission is largely the opposite from the Homecoming mission.
 * Mithrax only aids you once at the very beginning of the mission and isn't seen again until the very end.
 * Though enemies of the mission are loyal to Eramis, a Fallen Baroness seeking to reestablish the House of Devils, all enemies encountered have the colors of the House of Dusk.