I present several challenge cases to Knowledge Counter-Closure based on inference from a true-but-unknown premise and discuss their significance. I argue that Keith DeRose's attributor contextualism and Jason Stanley's interest-relative invariantism face problems preserving Knowledge Counter-Closure. I close the chapter by examining Branden Fitelson's argument for the possibility of knowledge from essential falsehood. I show that our examination of knowledge from true-but-unknown premises provides the resources to respond to Fitelson's arguments, and underwrite the view that knowledge from essential falsehood is not genuinely possible.