I guess this is the book written by Salanie, whom I met once. He is obviously the type of very smart French with rigor training in Maths. I read the first edition two years ago. It was a nice introductory book to the field of contract theory. the part of static contract was well written but the part of dynamic contract was of poor quality. This version adds some empirical stuff and becomes better.
anyway this is in my mind a very nice book to read when you just enter this field. for more advanced readers, i recommend the book contract theory by dewatripont and bolton.