Last year, I physically stopped a passerby from walking into a moving car. I don't think this is an exceptionally good thing because it isn't. Many other people would do the same under the same circumstances. It is an instinct, and no thought went into it. Peter Singer asked the question - if saving someone nearby is so obvious, then why not save someone else who is far away if you are capable? 
 This book (really a collection of shorter pieces) is about 'do-gooders'. For lack of a better word, this is about people who would do charitable and kind things far beyond normal expectations, to the point where it affects their own livelihood. This includes founders of leper colonies, foster parents of multiple disabled children, nurses who volunteer in war zones, people who donate their kidneys to strangers, and so on. MacFarquhar keeps a respectful distance, avoids speculation as to their motives, and lets their stories unfold. Most are not fanatics to some believe, but feel compelled or perhaps duty-bound to do so. Their reasoning is a tonic to moral apathy, or salting the wounds that one isn't doing enough. 
 MacFarquhar adds some chapters on moral philosophy - Kant on the difficulties of universal ethics badly applied, for example, or the rise of justifications for selfishness from 'social Darwinism' to Ayn Rand. In these 'do-gooers', she finds moral utilitarians - like Singer, again, who says that every coffee cup bought here is a snatch of food stolen from a starving child, she finds that these people are maximizing their moral output. 
 But this still raises feelings of discomfort - of course it is an impulse to help another, but what if that begins to hurt those closest to you? People who would give charitably where it hurts their own families, or the leper colony founders who put their own children at risk. Does this stem from a want to suffer? The effect is disquieting, that these do-gooders are not quite like us. 
 A serious investigation into moral lives and actions.