What Atom Requires

From the entrance of The Nucleus, head south through deactivated decontamination arches. You can find the note "Repairs in Progress" which adds the sub-objective to "Help Sister Mai." Continue south through blue double doors to a dry dock with a submarine.

Ignore the submarine for now and continue south into a shack to find Fusion Cores and junk.

Continue past some stairs to the south, then turn west to find Zealot Ware. He admires Brother Devin's devotion but asks you to convince Devin to abandon his faith. This starts the quest "The Trial of Brother Devin." He will give you "anti-RAD meds" and the recipe upon completion.

Continue west, then turn south up stairs before turning east into shacks to find The Archemist (the local doctor) and Zealot Theil.

Further east, find Sister Mai, the general store merchant. She sells the unique armor piece "Recon Marine Right Arm" (10% movement speed increase). Offer to help her, and she will direct you to the Vim! Pop Factory, starting the quest "Ablutions."

Head up stairs behind Sister Mai's store (south) to find Brother Kane, who sells weapons and armor, including the "Kiloton Radium Rifle" (Explosive prefix) and the "Recon Marine Left Arm" (slows time at low health).

Continue east to find the note "Taste Test."

Ignore stairs leading up to the command center (covered in "Best Left Forgotten (DiMA's Memories)"). Instead, head downstairs back towards Zealot Ware. From him, head north up a ramp, then up stairs and through shacks. Near a shrine, on an overturned chair, find the note "Put It From Your Mind," which mentions "holy bombs" in the submarine.

Continue north to find Grand Zealot Richter. He will give you a quest about a former cultist who joined a new club. Accept the quest to start "The Heretic," and speak to Zealot Theil for more information.

Head east from Richter to reach the submarine and a ladder into the "Vessel." Talk to High Confessor Tektus. Show him the Mother Icon if you haven't already. Ask him for help, and he will entrust you with rooting out a traitor, starting the quest "Witch Hunt." You will receive the "High Confessor's Note."