Topher and his father are trying to get over the death of Topher's mother, an Egyptologist, when they take in a stray cat. This cat bears an uncanny resemblance to a cat ornament given to Topher by his mother and so they name it 'Ka', meaning 'double'. Topher becomes very attached to Ka and is puzzled by her mysterious absences. One day when he is playing a computer game with an Egyptian theme, Ka jumps on the keys and spells out the name Bubastis, which was the centre of cat worship in Ancient Egypt. Could Ka really be leading a double life and what is she trying to tell Topher?
Ka, the time-travelling cat, has disappeared, leaving just one clue. Topher soon realises that she has gone back to Elizabethan England, and he fears that Ka is in terrible danger. Cats were tortured in Tudor England, so Topher must try to 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 elusive Philosopher's Stone.
An exciting and transporting fantasy, exploring both contemporary and ancient issues.