Reddit reviews The Reformation: A Very Short Introduction
We found 2 Reddit comments about The Reformation: A Very Short Introduction. Here are the top ones, ranked by their Reddit score.
Oxford University Press
This volume by Owen Chadwick may fit your bill in terms of page range.
Hillerbrand's a big name in Reformation studies. He wrote this ~500p. volume on the 16th century. His anthology of writings from the era is also very useful.
Diarmaid MacCulloch's the Reformation exceeds your page range (~800) but is very entertaining and gives a good overview of the world leading up to it. I think it's conceptually ambitious because it discusses the Reformation's effects on early Modernity in the 18th century.
On the other extreme of the page range (< 200 p.) is this Oxford Very Short Introduction by Peter Marshall. I like this series quite a bit, and I liked Marshall's emphasis on placing the Reformation in its political and social context.
If you want to focus on doctrine and theology, Jaroslav Pelikan's volume (~500pp) is highly acclaimed (along with his entire Christian Tradition series.)
If you want a short introduction or a documentary its all up to you. But Luther is a 10 0000 word journey. A journey into a unique insight into the world that were before us, and indeed shaped the world that is today. Brand Luther is also a start.