Just old stories

"There were dragons a long time ago. Some say that there were great, grim sky dragons that nested on the clifftops like gigantic, scary birds. Little brown scuttly dragons that hunted down the mice and rats in well-organized packs. Preposterously huge sea dragons that were 20 times as big as the big blue whale. Some say they crawled back into the sea, leaving not a bone nor a fang for men to remember them."

"But some of them weren't this cautious..."

This book takes time after the httyd3, but it occurs on the modern days, so no hiccup or toothless. Just their successors.