There are those of us who help and those who live to help. In Strangers Drowning, celebrated journalist Larissa MacFarquhar digs deep into the psychological roots and existential dilemmas motivating those rare individuals practising lives of extreme ethical commitment. The donor who offers up her kidney to a complete stranger; the activist who abandons possessions to devote himself to the cause; the foster parent who adopts dozens of children: such do-gooders inspire us but also force us to question deep-seated notions about what it means to be human. How could these do-gooders value strangers as much as their own loved ones? What does it really take to live a life of extreme virtue? Might it mean making choices as heartbreaking as the one in the old philosophy problem: abandoning a single family member to drown so that two strangers might live?