Iron Falcon '75: The Lakeside Adventures

Iron Falcon is a game by Chris Gonnerman that quite accurately emulates OD&D plus the Greyhawk Supplement. It has been out since 2015 and you can get it here in pdf for free or you can purchase a hard copy if you wish.

Chris Gonnerman now brings you an adventure called  Iron Falcon '75: The Lakeside Adventures. The premise is this:

What if magic was real? What if, long ago, monsters walked the Earth... ogres, giants, dragons, and vampires, and the smaller, scarier things that haunt the darkness? What if heroes and wizards did battle against them, in defense of humankind? What if the magic went away? What if it all just faded into the shadows? What if all the monsters and magic became nothing more than myths or superstitions, remembered by few and believed by even fewer. What if it all came back? What if monsters once again stalked the night, slipping out of the shadows to slay the unsuspecting and the skeptical? And what if a few people knew, and went out to fight against them? This is Iron Falcon '75.  In this game, players will take on the roles of modern-day people of the year 1975. No one but a crackpot would believe in magic, or giants or dragons or any of that nonsense. Yet your player characters will enter this world of magic and mayhem, willingly or otherwise, and do battle with monsters they once thought were just myths! This book includes background materials, supplementary and optional rules, and three adventures to get your campaign started. You will also need a copy of the Iron Falcon Rules for Classic Fantasy Role-Playing in order to use this book. The time has come to face what lurks in the shadows...

I don't use adventure modules directly, but when something good comes along, I do read them for inspiration. This looks to me to be one of the best, well worth reading and borrowing from and if playing through modules is your thing, this as I said looks to be one of the best of the genre.