(5) Tree Line
Dick Lehr and Gerard O'Neill are journalists by trade, so their writing style is as smooth and silky as a D'Angelo single. No impenetrable metaphors or page-long paragraphs here.
That being said, the story told by Black Mass spans decades, so there's a ton of info to keep track of. It might be hard to follow at first, but once you get familiar with the cast of characters, the book reads like a dream.