A woman named Alice sends an email to her friend Bob in which she shares her interest in astronomy. It appears to be a conversation between two amateur astronomists. However if one lists the first letters of all words, then reads the extracted sequence of letters in decimal expansion of π, and finally replaces each letter with the letter that precedes it in the alphabet, different message appears. The hidden message is unrelated to the content of the letter, which only serves as a cover to hide the very fact that a secret message is being sent.