The mission titled Free Their Minds, the Rest Will Follow will begin after you complete the task named Dead Kings and Pretty Things. This is one of the storyline missions available in Assassin's Creed: Odyssey Fate of Atlantis.
This mission revolves around releasing enslaved mortals in three locations: Minos's Faith, Pheraia's Retreat, and Deukalion's Heritage.
The first location you need to visit is called Adonis's Gardens. You must stun the enemies and then free them from Persephone's powers. Remember to do everything quietly.
In the Iphigenia's Compound location, you will also have to free the hostile characters from Persephone's grasp.
The last location that you need to visit is the Mausoleum of the Kingless Queen. There are eight more warriors waiting for you there.
Remember, that even if you have previously cleared these locations, the enemies will appear within them anyway.