The sixth and final installment of New York Times bestselling author Megan Miller's S.Q.U.I.D. Squad series. The S.Q.U.I.D. Squad is made up of three bold children who are part of a secret, underwater society of Book Guardians. They combine their unique talents to solve mysteries, right wrongs, and explore the oceans!   While settling into their new base at Ocean's End, life returns to business as usual: books are being delivered and stored and everyone is at work. The only n