When Daring Do visits her old pal A. B. Ravenhoof, the ex-adventurer reveals that there may be more in the sky than meets the eye....Somewhere above Equestria floats a cloud city completely hidden from sight by ancient magic. Legend says the hidden kingdom is home to a unique type of Pegasus, along with a mysterious treasure called the Halo of Cirrostrata.As soon as she learns about it, Daring Do can't get her head out of the clouds! She has to see it. But how? Many dangers...