Visions in the Fog

 is a main quest in the Fallout 4 add-on Far Harbor.

Synopsis
To join the Children, the Sole Survivor can't just mosey up and ask. To do it, they need to pass a test and bring back a token of proof to Grand Zealot Richter.

Walkthrough

 * 1) Witness the debacle at the entrance to The Nucleus and talk to Richter.
 * 2) Travel to Atom's Spring and drink.
 * 3) Follow the ghostly figure to the Children of Atom Shrine.
 * 4) Enter the little adjacent metal hut protected by ghouls.
 * 5) Read the periodic table on the wall (or rather, the scrawls next to it) and use the terminal on the cage.
 * 6) Collect the Mother Icon.
 * 7) Return to Richter.