"All Summer in a Day" is about life on the planet Venus. Apart from the one day every seven years that the sun comes out, it is always raining.
The short story begins with a classroom of children staring out of a window. Being Venus-born, none of the children are old enough to have ever seen the sun, except Margot. Margot was brought to Venus from Earth when she was old enough to remember the look and feel of the sun. As predicted by scientists, the sun only shines once every seven years on Venus. The day on which the story takes place is one of those days.
All of the students are crowded around the window waiting for the rain to abate. Margot, in particular, is very excited. She reminisces aloud about the sun, saying it looks like "a fire in the stove." Margot's classmates are too immature to understand or believe her, so, out of malice, they lock her in a closet. The teacher enters to inform the children that they only have two hours to play before the rain returns. The children go outside and play in ecstasy, enjoying their first day of sunshine. However, when they return to the classroom, they all realize they forgot Margot. Ashamed, the children stand glancing at each other for a few moments before they let her out of the closet.