La fuerza de un alma

Don't get baited by the shiny main quest symbol shown in Prydwen City/Monarch's Bluffs. It is the main story quest for this area.
Make your way towards Everfall: over all main story quest, you can pick your faction there and Mount Quest My Kingdom for a Horse (Lv 25).

Yonas Alazar sends you into Everfall.

As soon as you crossed the border, pick up the side quest No Good Deed from the cart.
Recover 3 Overripe Corn from the enemies in the Fallowhill Farm Area.
After this, follow the wolf tracks. Kill 3 wolfes and recover Riker's pack.

Make your way towards the Tomb of the Old Warrior to find the Soulwarden Temple.
Directly enter the Tomb of the Old Warrior, you will find all 8 temple guardians to defeat inside.
Inside: Read The First Promise. Ascend higher into the temple.
Read The Second Promise.

The next part of the quest is an event: Interact with the glyph to start the Trial of the Old Warrior.
As soon as you survived the trial, the wall behind the glyph will open and your next task is to defeat The Remnant.
To start the fight, slay all Inert Remnants around the actuall named enemie.
After: Read The Third Promise.

Just jump down from the building now and look for Yonas along the road. But you will only find Grace O'Malley.