Scorched #AtoZChallenge

I pulled a random book off the shelf in Great-Grandma's locked library. The key to the library had been handed down to me after her funeral. As the matriarch of the family, the bequests were spread thin. My part of the family heritage was a key. An odd inheritance, but G.G. was a wonderful, eccentric woman and I was excited to have a key to the locked room no one else could enter.

I looked at the faded gold-foil title on the book's spine: "Centuries of Sentries". Odd title. The aged leather was embossed with a flying dragon soaring across the bluish front cover. Odd imagery for a book of ancient guards.

The front cover was too heavy to lift one-handed, as if lined with lead on the inside. I set the tome spine-down on the big reading table, and let gravity aid me in lowering the front and back covers. Sure enough, the covers fell open with a BANG, as flames burst out from the middle pages! One short burst, then the fire vanished into thin air, but my fingertips were scorched. I blew on them, flicking my thumbs across the pads of my fingers. I could smell that the hair on my arms had been singed, too, although I didn't see it burn.

What kind of book was this? Now that it was open, I gingerly turned the yellowing pages to the front of the book. 
Aha. 
Here we go. 
Title page.

CENTURIES OF SENTRIES
A Guide to Our Majestic Dragon Guardians

Dragons? Sentries? There was no publication or copyright date on the following pages, but the language and imagery implied the medieval period or earlier. I sank into the chair placed in front of the reading table and turned page after page. The book had sketches of various types of dragons, and outlined the genealogy of some of the - apparently - notable sentries who had guarded against powerful foes.

As the sun dipped low and the room darkened, suddenly the oil lamps hanging from the walls of this room lit up of their own accord. Startled, I looked around. I had lost all sense of time as I read in this library. What was my G.G. up to? Why had she granted me the key to this room that had been a mystery to all of us when we were kids running through her big, old house during family events?

I knew I'd need to spend considerable time searching through the books and papers held within these walls, if I was ever going to find any answers. 

Thank you for visiting my #AtoZChallenge! My theme is "Audience Participation" (read about it, here) and now it is your turn. Each day will be a new story based on suggestions from your comments. Suggest anything: a word, scenario, character, location... I will be keeping a list of suggestions, so if yours isn't used tomorrow, it may show up later.

Today's post was inspired by the prompt "an ancient book about dragons", suggested by J Lenni Dorner (of Operation Awesome), given in comments on my Q post (here).