Where is The Whisper?
Children of Danu
Is dropped by The Mist
"Investigate Boyne Tombs, a forested hill west of Rathdown Trade Post in northern Meath."
Clue 2 is found above ground in Boyne Tombs camp.
"Investigate the stone ritual circle near the small harbor along the Boyne River."
Go to the harbor fast travel point west of Boyne Tombs.
Right by the fire nearby is Clue 3
She can be found roaming the boglands east of Inchroe.
Now you can mark her as target.