Sometimes, that's all you need to get a story rolling.
Now, I thought I had discussed this idea on here somewhere before, probably in the comments to this post on Great Openings to Novels; but it's not there; not anywhere on the blog that I can find with Google. Very strange.
Oh well, this is the latest of my ideas for a novel, and the one that I currently feel most interested in actually trying to write (although I suppose I've been pondering it for a bit over a year now, and haven't got down to making a proper start on it).
I was thinking about opening lines, and suddenly "Nobody dreams in here" occurred to me. I really liked it. And it immediately suggested to me a prison setting - the most obvious implication being the metaphorical dimension of 'dreams', that long-term prisoners do not dare to imagine their future freedom; the bleakness of their environment dehumanizes them, stifles their capacity to look forward with hope.
But.... that opening line suggested to me an opening paragraph describing the typical beginning of a day in this prison, the protagonist suddenly returning to consciousness after a night of dreamless sleep. Actual dreamlessness. I suddenly pictured the entire prison population all waking at exactly the same moment (roused by a buzzer or klaxon), none of them being able to remember any dreams. How might that happen?
And so, what had started out as an idea for a fairly conventional and realistic prison story abruptly evolved into a more mysterious and surreal fable with a Kafka-ish quality. I envisaged a prison population who had all forgotten what crimes they had been imprisoned for, but rarely contemplated or questioned this puzzling fact. Moreover, they faced daily interrogation sessions which were ostensibly directed towards encouraging them to remember - and acknowledge and express remorse for - their offences, but which in fact seemed to be merely encouraging extended reminiscences about whatever they could remember of their lives before prison.
Why have their memories become so frail and fragmentary? And why are their memories so important to whoever is in charge of the prison? And why have they lost the ability to dream?
I always find, when developing a story idea, that if I ask questions, the answers come to me. And the answers build the story.