This is a Hades (Act IV) Side Quest.

Callicrates has another job for you
The shades of these Plains are not heroes, but they do what they can against the daemon army. Callicrates says that someone named Keuthonymos is the mastermind behind these operations. To get in touch with him, it is necessary to talk to Pylades first.
Walkthrough
Note: Callicrates will offer this quest only after his other quest, An Invitation, is completed.
- The quest begins after a conversation with Callicrates in the Upper City of Lost Souls (he is in the upper right corner of the western hall).
- Then, a dialogue with Pylades (near the eastern exit of the city) must be had.
- As soon as hero reaches the Lower Daemon Camp from The Salt Flats, he must turn LEFT. There is a neutral Machae there who wants to talk. His name is Keuthonymos, and he will ask for a favour. He wants the hero to find and eliminate a daemon envoy who's is carrying a very important message.
- The envoy's name is Kor-Lhrut, and he is walking along the road upon entering Vale of Mourning, right past the Upper Daemon Camp. When defeated he drops a Daemon Scroll.
- The quest will be completed, when this message is returned to Keuthonymos.
Reward
- 34000 / 78000 / 210000 points of experience (normal / epic / legendary)
- a random Relic shard
Gallery
Act IV Quests
A Mysterious Message • A Crab Story • An Impossible Task • The Torch-Lighter's Gauntlet • Outpost in the Woods • Medea's Price • The Stolen Sigil • The Wealth of Ancient Kings • Lampido's Potion • The Treasure Hunters • The Road to Hades • Among the Ruins • A Dangerous Mission • The Enemy's Captain • The Stygian Lurker • One Who Would Lead • Judgment of the Living • Hades' Treasury • The Dust of a Titan • Eurydice and Orpheus • An Invitation • The Necromanteion • Admetus Among the Dead • An Inside Source • The Battle for Elysium • The Siege Striders • Flight of the Messenger • The Achaean Pass • A Noisy Diversion • The Immortal Throne • The Shards of Erebus • Hades' Generals