When one steps into the theatre, there's an unspoken agreement to suspend disbelief, to let the world of the stage envelop you. Walking into the National Arts Centre to watch Broadway Across Canada's Hadestown, my disbelief was suspended, mostly because unlike previous shows I've seen, I had no background about this play. I was armed with little more than curiosity. And as the final notes faded and the curtains descended, I found myself in a contemplative trance, thinking, "Well, I'm still not …