All the stories are real. All the Gods are too, and the Greek versions are no less real than any of the rest. But something happened, something to make them begin a war with each other, and it would have turned the world into chaos, but before any blows had been struck, Hecate stopped it all. With her witch-like powers, she ended the war before it began - or at least put a pause on it. The mortal world didn't need to know they were real, they didn't need to be thrown into the midst of battle because of issues between the Gods themselves. They didn't deserve that, so she did what she had to do to save them, and the world they lived in. In the blink of an eye, the Gods disappeared - but not completely, instead they were turned into mortals themselves, but mortals with locked memories and abilities that seemingly started up out of no where, abilities they didn't understand. Her spell worked too well, it seemed, as every other thing thought to be a myth, legend, or fairy tale were locked away in the town she created as well, their own memories forgotten, their own lives left behind.
The plot is loosely based off of Once Upon A Time, the ABC series with a few differences.