That is what I would call an "idea" for a story. Around it I would build plot, detail, incident, characterization, etc.
Katharine Holland Brown: Once in a long while a story begins as a situation: as a tangle, a conflict, to be unwound, fought out. But almost always the story arrives as a whole—without any planning whatever, the story is suddenly there, a big blurry mass of pictures and incidents and action, that must be splattered down in black and white as fast as you can possibly write. It goes racing by like a runaway movie film and the best you can do is to snatch at the most significant moments, before they escape. Therefore the idea for a story is not an idea; it is the story itself. (With a serial, which must have a succession of ascending climaxes, a rough outline is made and followed, after the big scenes and the principal action are jotted down.)
F. R. Buckley: The genesis of a story with me is likely to be anything. Occasionally a character; more often a title; more often still, a good basic situation, up to and from which the story can lead; most frequently, an ending. Story I liked best, Archangel in Steel, deduced from setting and period: Florence, XVI century; connoted an age of plotting and intrigue; since plots were villainous, hero must be anti-plotter. History supplied the conspiracies; the story consisted of the hero's counter-actions.
Prosper Buranelli: My first idea is always an incident or a situation, sometimes several to be combined. Or a generic situation in some phase of life—such as an opera singer's being at the mercy of the orchestra conductor.
Thompson Burtis: I have had stories come to me as a result of all the things mentioned in your question, except a title. And I'm about to try to construct a story around a title. The most usual starting-points for stories with me are either incidents or characters. In a large percentage of cases I start with an incident and then work my main character into it with regard to his particular traits.
George M. A. Cain: A story almost always takes its genesis with me from a situation, sometimes suggested by an incident, character, trait, setting, title, anything. Unless any other feature can shape itself readily into a situation for me, there is no story. But the situation may not mean the beginning of the story as told. I may write the whole story to get that situation.
Robert V. Carr: The question involves, at least to my understanding, chemistry, heredity, environment, psychological wounds, tricks of memory, and a thousand and one mysteries. No doubt there will be writers who will cleverly announce that they know exactly where they secure their ideas, but it is beyond me. The writers of motion-picture scenarios should be able to tell you in a few words where they get their ideas. For my part I do not know the true genesis of any idea.
George L. Catton: A story with me may grow from, to begin with, the merest trifle. Sometimes I start with a character only; other times perhaps it is a title, or a peculiar characteristic of a character, a situation or a setting. But the big start for me, the start I always try to get, is a theme. It's a poor story I'll write if I can't put down the title before I write a word. I never wrote a story yet that didn't have a theme, and I never will. A story without a theme is a story without a soul, and is just about as much use as a man in the same predicament. An idea for a story with me, then, is a theme.
Robert W. Chambers: From an incident.
Roy P. Churchill: Most of my story ideas come from what I call a "condition" for want of better expression. That is, affairs of life in a certain setting, with certain characters, assume a "condition" which makes for the unusual.