Robert E. Howard 
The Shadow Kingdom [EPUB ebook] 

‚The Shadow Kingdom‘ by Robert E. Howard is a sword and sorcery tale featuring Kull, the warrior-king of Valusia. As Kull ascends the throne, he soon discovers that his rule is threatened not just by political intrigue, but by ancient and inhuman forces. A race of serpent-men, capable of shapeshifting to impersonate trusted allies, plots to overthrow him. With the aid of Brule the Spear-slayer, a Pictish ally, Kull must navigate deception, face monstrous enemies, and uncover the dark secrets that lie beneath the surface of his kingdom.