People lie. Lies permeate every aspect of our lives—from advertising and politics to medicine and education. Is society to blame? Or is our brain naturally wired to distort information? Where is the line between self-deception and optimism? And in what situations is untruth more valuable than truth? Science journalists Shankar Vedantam and Bill Mesler show how deception has shaped humanity and reveal the role lying plays in the modern world. Drawing on scientific research, crime reports, and anecdotes, they explain how to benefit from delusions and stop dismissing others as crazy for their strange views. And why the truth isn't always what it seems.