Ka, the time-traveling cat, has disappeared, leaving just one clue. Realizing that she has gone back to Elizabethan England, Topher fears that Ka is in terrible danger. Cats were tortured in Tudor England, so Topher must find her before it is too late. In doing so, he meets Queen Elizabeth and Doctor Dee, the court magician and astronomer, who thinks Ka can help him find the Philosopher's Stone.