If I know anything (and I don't) then that road leads to the ancient cavern where you'll need to fight the Lizard Man King in order to get the Mystical Key III. Use the Gold Sword II. You'll lose, but he will tell you that it was the best fight he's had in decades and give you the key. You can then go past him into the cavern where your quest continues. Open the ancient chest just on the other side of the door (the door will slam shut and lock) to find one fresh apple, one hot stew, and three lit candles.