A witty, provocative, story-filled inquiry into the indispensable virtue of loyalty—a tricky ideal that gets tangled and compromised when loyalties collide (as they inevitably do), but a virtue the author, a prizewinning columnist for The Wall Street Journal, says is as essential as it is impossible. Felten illustrates the push and pull of loyalties— from the ancient Greeks to Facebook—with stories and scenarios in which conflicting would-be moral trump cards trap the unlucky in painful ethical dilemmas. The foundation of our greatest satisfactions in life, loyalty also proves to be the root of much misery. Can we escape the excruciating predicaments when loyalties are at loggerheads? Can we avoid betraying and being betrayed?

When looking for love and friendship—the things that make life worthwhile—we are looking for loyalty. Who can we count on? And who can count on us? These are the essential (and uncomfortable) questions loyalty poses.

Loyalty and betrayal are the stuff of the great stories that move us: Agamemnon, Huck Finn, Brutus, Antigone, Judas. When is loyalty right, and when does the virtue become a vice?

As Felten writes in his thoughtful and entertaining book, loyalty is vexing. It forces us to choose who and what counts most in our lives—from siding with one friend over another to favoring our own children over others. It forces us to confront the conflicting claims of fidelity to country, community, company, church, and even ourselves. Loyalty demands we make decisions that define who we are.