"Wild nights are my glory, " the unearthly stranger told them. "I just got caught in a downdraft and blown off course. Let me sit down for a moment, and then I'll be on my way. Speaking of way, by the way, there is such a thing as a tesseract."
A tesseract (in case the reader doesn't know) is a wrinkle in time. To tell more would rob the reader of the enjoyment of Miss L'Engle's unusual book.