I am searching for books about mathematics in Hebrew which can further interest a 13 year old boy only casually interested in mathematics. These books should not just tell about mathematics, but should show "how it works". There should be some simple proofs inside explained in a conversational and informal style. There should be some surprises, more or less easy to understand, and mysteries. There can be stories inside like that of mathematical duels of Tartaglia, Kepler searching for laws of nature, and the beautiful proof which alas the book's margins could not contain..
When I was a boy, there were the books of Avraham Halevi Fraenkel, which got me much interested in set theory, calculus and other topics, though they were then above my head.
I tried to look for such books, but it is hard for me to find one which I would like (often today's popular science books are composed of "pieces" without a unifying idea), and Fraenkel's books in today's Israel look a bit anachronistic, though I guess I can find them in second hand shops. Besides, something simpler would probably be a better fit.
So I am asking for possible suggestions.