Yurt the Silent Chief is a rather interesting case study in the lore of Demon's Souls.
As the leader of a secret band of assassins - hence the "Chief" in his name - and clearly locked up tight for a reason, Yurt is no stranger to death and murder. Yet, in the context of the full Demon's Souls narrative, is he a helpful NPC or just another adversary to the slayer of demons?
Imprisoned in the Upper Cathedral Ward of the Tower of Latria, held within the smallest of cages dangling high above the Prison of Hope, this imposing Gloom Armor-wearing mercenary may at first seem to be a character not to be messed with. Wielding a menacing shotel in one hand and a small dagger in the other, Yurt is certainly a formidable foe for newer players and his story is one of the many things you should know before starting Demon's Souls.
How exactly he got locked up, however, and who exactly did it remains a mystery. Theories abound on this unknown point in the Demon's Souls narrative, ranging from his being captured in an attempt to either kill or save high-ranking members of the Soul Industry, who were jailed in Latria by the Old Monk. Or, yet another concept points to the simple yet plausible idea that he mistakenly rode the cage up to the top of the Tower, only to then realize he could not reach through the bars to unlock the latch.
The slayer of demons will run across Yurt on their journey through 3-2, not mere moments after breaking the first chain holding in place the beating mechanical heart of Latria. To reach Yurt's cage, you will have to drop down to a lower, now broken part of the walkway once long before connecting the two platforms together.
Be careful not to accidentally fall off the side; it's easier to take the light jump to the left of the walkway rather than leaping straight ahead, as you are more prone to miss the landing and die a painful death. It's best to go equipped with either a shard of archstone or the miracle called Evacuate, otherwise, you have no other way of leaving the platform other than freeing Yurt and utilizing his cage as an elevator to continue onward deeper down into the hopeless Tower of Latria.
The question, then, is should you free him or should you kill him? Honestly, this is one of those many things only pro players know. Yurt, as mentioned previously, is a dangerous mercenary, whose aptly-named title of Silent Chief references his rank among assassins and his ability to remain both unseen and unheard in his murderous deeds. Thus, when standing before his locked cage and hearing his sweet words of potential companionship, many new players fall into the trap of believing him.
Upon first meeting Yurt, he tells the player, "Are you here to fight the Demons? If so, then help me escape this place. I am on your side. I have come to face the Demons." Don't listen to a word of this. It's best to just free him from his cage and kill him where he stands. If you free him and allow him to return to the Nexus, he will begin systematically killing all of the NPCs inhabiting this supposed "safe zone."
As an assassin for hire employed by the evil Mephistopheles, Yurt is certainly an imposing force of death-bringing, but he's not a hard target to defeat. You can use magic or simply return to the Nexus after freeing him and kill him there. Some players have even cheesed him by using Evacuate after opening his cage, returning to the Tower of Latria, and, standing just above his location, hit him with an arrow to draw him off the edge.
Upon his death, Yurt drops the poison and plague resistant Gloom Armor set, which will come in handy when traversing the poison-filled swamp of 5-2, or the Swamp of Sorrow. Beyond this and looking pretty sweet on the player, the Gloom Armor also has a relatively high physical defense rate of 34, so it's good to equip for lower-level and newer characters, so long as you have a high enough equipment burden to don it.