Unique perspective on an interesting life. Macintyre explores Kim Philby's life as a double agent for the USSR through his friendships with colleagues in MI6. The book is fascinating in that it offers no definitive answers as to why Philby betrayed his country or how he was able to divide himself between his inner life as a Soviet operative and his outer life as an MI6 agent. The book is obviously well researched with great sources and interviews of people who thought they knew Philby best. If you're willing to wade through the alphabet soup of intelligence agencies and operations, it's worth the read.