Mass Fusion

Speak with Allie Filmore by the elevator. She will join you for the mission.

Use the elevator to reach the relay device. You will receive a warning that relaying to Mass Fusion will make you a permanent enemy of the Brotherhood of Steel. Confirm to proceed.

You will arrive in the Mass Fusion Executive Suite. Engage the Brotherhood Scribes and the Knight in Power Armor outside. Allie will distract enemies.

Head inside and up the stairs to the third level. Pick the [Advanced] lock on a door to find a First Aid Box and other items. Search the outside area for another First Aid Box.

Return to the second level. Find the "Oslow’s Office Recording" holotape and listen to it.

Hack the [Advanced] terminal in the same room. Read the first email to learn the Beryllium Agitator is in the reactor and requires the "Executive Keycard".

Leave the room and find the "Mass Fusion Executive Lab Password" and "Mass Fusion Executive ID" on a nearby desk.

Use the Executive ID on the middle elevator to access the main Mass Fusion building.

As you descend the elevator, you will be ambushed by Brotherhood soldiers. Use VATS and sneak mode to eliminate them.

Upon reaching the floor, defeat the Knight in Power Armor and Scribes.

Enter the north room and pick up the "Mass Fusion Labs Key" from the table.

Hack the [Expert] manager's terminal in the same room to reroute power and complete the optional "Restore Power" objective.

Head east from the glass floor, turn right, and follow the path to a destroyed balcony.

Hug the wall to the right to find a room with a blue console. Search it for a copy of Tesla Science.

Alternatively, head to the northeast corner and use the [Expert] locked door (or the key you found) to proceed downwards.

From the lower floor, go up the left steps and enter the left door to find an elevator with a keycard reader. Use the keycard and descend.

Allie will point out the reactor. Before heading there, go through the south door.

Hack the [Novice] "Prototype Lab Terminal" and turn on a Protectron unit. Kill the Protectron.

Take the north door to another office area. Hack the [Advanced] "Attendant’s Terminal".

(Optional but recommended) Mine the two doors across from the terminal if you have explosives.

Use the terminal to activate the Assaultron Units. Defeat them when they emerge.

Activate the turrets using the terminal. Shoot down the turret above the terminal and the one in the southern room.

Loot the locker room to the south and the bathrooms beyond for a First Aid Box.

Return to the reactor-viewing area. Loot the Steamer Trunk at the end of the left balcony.

Note the mag-lock doors on each balcony and the hallway underneath the stairs.

In the hallway, find the "Analyst’s Terminal" [Novice] and a [Master] locked safe. You can unlock the safe with the terminal. Free and kill the Protectron.

Equip a Hazmat Suit (found in the locker room if you don't have one).

Make your way to the decon room and hit the button. Enter the reactor.

Proceed to the reactor core and hit the button to pick up the Beryllium Agitator.

Upon picking up the Agitator, shoot the two Laser Turrets on the ceiling to the west.

Head back to the decontamination chamber.