The Unyielding Flesh quest is a particularly gruesome one that you'll find early on in Diablo 4. It involves one of Ramsay Bolton's favourite pastimes—a flayed man—though the quest was a little buggy over the last Diablo 4 beta weekend. You get a unique weapon for your troubles and a bunch of gold and renown, but it is a little graphic. With that in mind, here's where to find the flayed man and complete the quest.
How to begin the Unyielding Flesh Quest
To get started, you'll need to be at least Level 7 and will need to have reached Kyovashad, which unlocks the path to Yelesna in the southeast. You're looking for a woman named Krystyna whose husband, Feodor, has gone missing. She overheard him talking to another woman, so you know it's gonna be a bad time. She'll accompany you, so follow the waypoint to the blue highlighted oval further southeast from Yelesna in the Gnarled Timbers.
Where to find the flayed man
You'll find Feodor roughly in the centre-left of the blue oval and you'll see that he's chained up and flayed—and he's rather pleased about it. The mysterious other woman says "may you know bliss eternal" about the whole no skin situation, so well done if you've already worked out that she's a demon in disguise. A blue marker will appear on your minimap, so follow it to confront her.
She'll turn into Yulia the Hellbound and to be honest, she's pretty easy to defeat. Once taken care of, return to Krystyna. She'll say you can take the dagger from Feodor's chest, which spills a good deal of blood everywhere. You'll get at least +20 renown, 1000 XP and a bunch of gold for finishing the quest, plus the Blood-barbed Blade dagger.