Plato's Republic is arguably the most famous and influential work of philosophy ever written. It is certainly among the most widely read and studied, a staple of undergraduate courses that continues to inspire and inform contemporary debates in political philosophy. As such, it is a hugely important and exciting, yet challenging, piece of philosophical writing.
In Plato's 'Republic': A Reader's Guide , Luke Purshouse offers a clear and thorough account of this key philosophical work. The book sets Plato's work in context, introduces the major themes and provides a detailed discussion of the key sections and passages of the text. Purshouse goes on explore some of the areas of thought that the Republic has impacted upon and provides useful information on further reading. This is the ideal companion to study of this most influential and challenging of texts.
Unfortunately not dealing with the entire book, but only the first part and a short chapter about the 10th book. So for the ones that want to follow the main arguments, ideas and thoughts across the entire book, look elsewhere. The books that are dealt with are good to follow and the arguments outlined perfectly. It's only that this book should have been 3 times thicker.
Probably Julia's Annas's An Introduction to Plato's Republic (Oxford 1981) is a much better book to serve the purpose of introduction.