“The Nuclear Option” is a main quest in Fallout 4 that involves working with the Minutemen to take down the Institute.
To begin “The Nuclear Option,” you need to have completed the Minutemen quests “Inside Job” and “Defend the Castle.” Once Preston Garvey deems the Minutemen strong enough to take on the Institute, he will direct you to Sturges for further instructions.
The Nuclear Option (The Minutemen)
Head to Sanctuary (or wherever Sturges is located) and speak with him. He has figured out a way into the Institute using the data you stole during “Inside Job.”
Sturges will give you the Institute Relay Targeting Sequence and an Automatic Laser Musket. This sequence allows you to teleport into the Institute.
Go to the irradiated river’s edge in the Cambridge Neighborhood, west of Greentech Genetics. There’s a Raider camp by the river that you may need to clear first.
Dive into the water, swim into the Public Works Maintenance Area, and activate the keypad. A hazmat suit or Power Armor is recommended to negate radiation. Open the grate and drop through the effluent pipe into the old sewer.
Follow the arrows marked on the walls, hack the security terminal (Expert) or pick the lock (Expert) to access the security door. Continue through the open inflow pipe to infiltrate the facility.
Infiltrating the Institute
Load the Institute Relay Targeting Sequence into the relay terminal. This will teleport Preston and a few Minutemen into the Institute.
Speak to Preston to receive the Fusion Pulse Charge, a device crucial for completing the mission. Your route will take you through the Old Robotics area, where you’ll encounter synth adversaries and laser turrets.
Drop through the hatch and enter the Institute BioScience laboratory. Navigate to the reactor entrance, where you’ll find the blast door activated.
At the central elevator, press the button to enter Father’s quarters and obtain the override password. Use it or hack the terminal (Novice) to activate the Master Security Lockdown Override.
You have three options when dealing with Father regarding why he should help you. Use your Charisma to resolve the situation with minimal casualties.
Final Confrontation
Head to the Institute Advanced Systems and enter the reactor chamber. Expect a cluster of synths and scientists. Access the reactor door and activate the reactor housing.
Sturges will teleport you to the Institute Relay Control Room. Speak with Preston Garvey before Sturges mentions an unplanned visitor in close proximity.
You can choose to take the visitor under your wing and ensure his safety or inform Sturges that the child must remain. Your choice will affect the ending of the quest.
After dealing with the visitor, activate the reactor and teleport to the roof of the Mass Fusion building. Press the button to trigger the spectacular light show, signifying the end of the Institute.
Finish the quest with a conversation with Preston Garvey about the future of the Commonwealth. This quest plays a big role in the Minutemen ending.
