Gathering Storms

Gathering Storms is a main quest in the Fallout: New Vegas add-on, Honest Hearts.

Detailed walkthrough
The quest is given upon completion of The Grand Staircase, The Advance Scouts, The Treacherous Road and River Monsters. When the Courier speaks to Daniel, he will give the Courier the option of either:
 * Helping the Sorrows evacuate Zion Canyon, beginning the quest Flight from Zion.
 * Fighting the White Legs with Joshua Graham, beginning the quest Crush the White Legs.

Telling Daniel which option he Courier has chosen completes the quest.