Derek Parfit, author of Reasons and Persons, has had a deep and lasting impact to moral philosophy. His life's work was to "rescue philisophy from nihilism". Along the way, he became influential in several modern effective altruistism movements. This book is a biography of his interesting life, that despite his influence, was spent away from much limelight.
Parfit was clever and deeply cared about ethics, though this biography largely just asserts his conclusions in between well-researched anecdotes of his life. So, if you have never read Parfit, this will unlikely be compelling. However, if you're a fan of his work, then it's a quite interesting view into his unusual life, and is a worthwhile read.