King James is most famous for putting together the King James Bible, but reading that doesn't give us much insight into his personality. That's where this book comes in.
Daemonologie takes the form of a dialogue between Epistemon, who believes in witches, and the skeptical Philomathes. However, Epistemon quickly convinces Philomathes that witches are real by quoting a few scriptures, so most of the book consists of Epistemon explaining the details of witchcraft with Philomathes merely prompting him to continue speaking. King James not only cites canonical scriptures, but also scriptures from the Apocrypha, which is no surprise since the King James Bible originally included the Apocrypha in 1611, not removing it until 1885.
Along the way we learn of the difference between necromancers, magicians, and witches. King James also goes into ghosts, werewolves, incubi, succubi, demoniacs, and fairies. However, he draws the line at the idea there is a good angel on one shoulder and an evil angel on the other shoulder of everyone. He tells us this isn't true. Apparently, His Majesty was not familiar with the Shephard of Hermas, an early Christian document considered canonical by many early church fathers which explicitly states just this idea.
He also tells us the Devil will sometimes possess a corpse and use it to impregnate nuns. How can you tell if the person trying to impregnate you is actually a possessed corpse? "It is to be noted, that in whatsoeuer way he [the Devil] vseth it, that sperme seemes intollerably cold to the person abused."
Also included in this volume are notes on the trial of Doctor Fian, a sorcerer King James put to death while King of Scotland. Here we learn that witches can cause hurricanes by using a cat somehow, that witches kiss the Devil's buttocks to pay homage to him, and that the Devil leaves his mark on a witch's privy members by using his tongue. Thus, to discover a witch, one must shave off all their pubic hair to look for the Devil's mark.
Torture is also a good way to get a witch to confess. One witch confessed to attempting to kill King James himself by hanging a toad upside down for three days to collect its venom. Her plan would have worked if not for the fact she wasn't able to gain access to King James' used laundry to complete her spell.
Doctor Fian, a school teacher, apparently fell in love with one of his pupils' sisters. He told the boy that if he obtained three of his sister's pubic hairs he wouldn't hit the boy like he did all of his other students. When the boy tried to obtain the pubic hairs, his sister woke up and called for her mother. Her mother, being a witch herself, knew what was going on, so she had her son give Doctor Fian three hairs from the udder of a cow. When Doctor Fian cast his spell, the cow was the one who fell in love with him and followed him around everywhere. There's even a woodcut in this volume depicting the scene.
Under torture, Doctor Fian confessed to being a witch. However, after escaping from prison and being recaptured, he renounced his former testimony and said he only confessed due to fear of further torture. Whereupon, King James had him tortured some more: "His nailes vpon all his fingers were riuen and pulled off with an instrument called in Scottish a Turkas, which in England wee call a payre of pincers, and vnder euerie nayle there was thrust in two needels ouer euen up to the heads."
However, so great was the Devil's hold upon Doctor Fian that he still would not confess. So he was put to death. Basically, if someone confesses to being a witch under torture, they're a witch, but if they don't confesses under torture, that also means they're a witch because only the Devil could make someone endure so much pain.
By the way, the person who wrote the forward to this book doesn't know what he's talking about. He refers to Elizabethan English as Old English, which it decidedly is not. I doubt other things he says as well. This book is a bit hard to read since it appears as it originally did in King James' day and spelling hadn't been standardized yet, but that also makes it fun to read as well.