Flight of the Messenger - Act 4 Side Quest
Start Location: Aetolian Polis
Quest Location: Delian Meadows
Objective: Take the messenger you're given to Ajax in Delian Meadows
Flight of the Messenger is a Side Quest which begins by speaking with Nestor in the Aetolian Polis, one of the final towns you visit during Act 4. If you've forgotten how to reach the Aetolian Polis you'll want to take the Elysium Portal to get here. You'll find Nestor northwest of the Portal.
All you need to do for this quest is to speak with Nestor twice and then deliver the messenger he gives you safely to Ajax in Delian Meadows. You'll find this location to the northwest of where the quest starts and I would recommend either killing all of the enemies between you and this quest prior to starting it or just running through all of the enemies to deliver the messenger.
Like all other escorts in Titan Quest, every enemy will go after the NPC you're escorting first rather than you. If you stop to fight too many enemies your escort will die. Thankfully, it doesn't matter if they die as you can return to Nestor and get another messenger as many times as you'd like.
Note: Completing this quest and turning it into Ajax will allow you to pick up the follow up quest, The Achaean Pass.