When Christopher Hope, Topher for short, finds an unusual-looking stray cat he longs for her to stay with him. But the cat has a mind of her own. She comes and goes, sometimes for days at a time. 'Where do you go, Ka?' Topher asks after a particularly long absence, and she replies - with a strange word on his computer! When she disappears again Topher sets off to find her. His quest leads him through space and time, to people and places he thought he would see only in books - and danger.