Mass Fusion Main Story, The Institute Quest
This quest will be triggered or can be aquired when you complete Mankind-Redefined quest.
Stages of "Mass Fusion" quest
1. Talk to Justin Ayo
This stage is optional. Quest will start here when you receive an order to find the Beryllium Agitator for the Brotherhood of Steel during Spoils of War quest.
The Brotherhood is going after something called a "Beryllium Agitator" in Mass Fusion. I need to let the Institute know.
3. Relay to Mass Fusion or Inform the Brotherhood
The Institute is after something called a "Beryllium Agitator" from the ruins of Mass Fusion. I should relay there as soon as possible.
Warning: Relaying to Mass Fusion will make you a permanent enemy of the Brotherhood of Steel.
If you decided to inform Brotherhood then go to Boston airport and talk to Proctor Ingram. It will start new quest - Spoils of War.
4. Locate the Beryllium Agitator
The Institute is after something called a "Beryllium Agitator" from the ruins of Mass Fusion. I should relay there as soon as possible.
5. Proceed to the Reactor Level
5.1. (Optional) Restore Power to the Elevator
6. Retrieve the Beryllium Agitator
After fighting my way through Mass Fusion, I've arrived at the Reactor Level. I now need to find a way to remove the Beryllium Agitator from the reactor.
7. Unlock the Reactor
8. Take the Beryllium Agitator
9. Eliminate Reactor Level Security
10. Exit Mass Fusion
With the Beryllium Agitator in hand, I should head back up to Mass Fusion's lobby and exit the building.
11. Speak with Allie Filmore
I've successfully helped the Institute fend off the Brotherhood's attack on Mass Fusion. I need to get the Beryllium Agitator to Allie Filmore.
12. Quest completed
The Beryllium Agitator is now safely in the hands of the Institute, ready to help bring the reactor online.
Next / new quest is Pinned (Main Story, The Institute).