During the night, Meg's younger brother Charles Wallace welcomes a stranger in a large white dress named Mrs. Whatsit into the Murry family house. She mentions the tesseract, a type of space-travel Alex was working on, is real, and leaves soon after. The next day, one of Meg's classmates, Calvin O'Keefe, joins them to go to the house of Mrs. Who, another strange woman who only speaks in quotes and seems to know Charles Wallace.