On a dark and stormy night, twelve-year-old Margaret Murry sits on the foot of her bed in the attic and watches the storm. Except for her, everyone in the house, including her twin brothers Sandy and Dennys, and her baby brother Charles Wallace, is asleep. Meg has had a bad day at school and cannot stop thinking about it. She is also upset about the fact that her father has gone missing.
The dog Fortinbras barks, and Meg remembers hearing about a tramp in the neighborhood who stole twelve sheets from Mrs. Buncombe, the constable's wife. She wonders whether the tramp is heading for their house. She goes downstairs to make cocoa and finds five-year-old Charles Wallace in the kitchen. Charles Wallace says he knew she would come down, and Meg wonders how he knew. Charles Wallace always seems to be able to tell what she is thinking. Everyone thinks he is dumb, but Meg and her parents know that is not so.
Mrs. Murry joins them in the kitchen. Meg no longer feels fearful, and her mother tries to encourage her not to feel so bad about herself.
Charles Wallace mentions someone called Mrs. Whatsit, and says she and her two friends live in a house in the woods that is said to be haunted.
Fortinbras growls, and Mrs. Murry goes to investigate what has upset him. Meg thinks it must be the tramp. Her mother returns with someone who does look a bit like a tramp, and is all bundled up in clothes. It is Mrs. Whatsit, who was out in the storm and realized she was passing Charles Wallace's house and thought she would stop by and rest. Meg is suspicious of this old woman, but makes her a sandwich anyway. Charles Wallace chats with Mrs. Whatsit, chiding her for taking Mrs. Buncombe's sheets. Mrs. Whatsit replies that she needed them, while Mrs. Buncombe did not. Just before Mrs. Whatsit decides to be on her way, she tells Mrs. Murry, who is a scientist, that there is such as thing as a tesseract. She offers no explanation of what she means, but Mrs. Murry obviously recognizes the term, and is shocked. She wonders how Mrs. Whatsit could have known.
This chapter introduces several of the main characters in the story and gives them distinct identities. It also introduces two elements of mystery, and subtly announces two of the main themes of the novel.
The personality of Meg in particular is sketched in some detail. She is very dissatisfied with herself. She does not do well at school and she thinks she is dumb. She doesn't fit in the way the twins Dennys and Sandy do. They are "normal," but she is not. She thinks of herself as an oddball. She hates her appearance (she wears braces on her teeth and her hair is all over the place).
Charles Wallace is also described in detail. He is unlike any five-year-old who ever lived. No five-year-old talks the way he does. Charles has his own kind of maturity and knowledge, but it is of a different kind than is recognized by conventional society. Everyone thinks he is stupid, but of course he is not.
The characterization of Charles is one of a number of ways in which the author shows the possibility of a way of communicating that does not use words. Charles Wallace, for example, understands what Meg is thinking and doing before she thinks or does it. There is no need for words. Indeed, Charles did not start to talk until he was four years old. Given his mysterious precocity, it is appropriate that it is he who discovers Mrs. Whatsit and the other ladies. It seems that Charles is in tune with another world, another way of being, so to human perception he appears strange or even dumb.
A couple of times in this chapter, it is clear that in the Murry family, no pressure is exerted on Meg and Charles to be like other children. Mr. and Mrs. Murry are content to allow them to be themselves. The importance of this will become clear later in the novel.
The first chapter also gets the plot moving, and supplies two touches of mystery: the unexplained fact that Mr. Murry is missing, and the introduction of a term that will not be explained until later.