Great overview of Hayek's thought. Although it is rather 'old', I would still recommend it to someone who wants to read about Hayek's philosophy. It is good as an introduction but it is also great for those who are already more familiar with Hayek to help place his thinking in the historical and intellectual context. It also helps to see the red threads in Hayek's thinking and to see it more as a whole. It also helps to see how Hayek's views relate to other contemporary positions.

Hayek's Social and Economic Philosophy by Norman P. Barry (1979)