Liars are Alex Gibney’s specialty: among the subjects of his best documentaries are such world-class prevaricators as Ken Lay and Jeff Skilling (Enron: The Smartest Guys in the Room), Jack Abramoff (Casino Jack and the United States of Money), and Eliot Spitzer (Client 9: The Rise and Fall of Eliot Spitzer). With this exposé of cyclist Lance Armstrong, however, Gibney focuses on a man so taken with his own legend that he considered himself above the truth; sanctified by his victory over cancer and his advocacy for cancer victims, Armstrong concealed his illegal doping with a self-righteousness that became cancerous itself, destroying his entire career. Gibney assembles a damning case against the athlete, but what distinguishes this from other accounts of the scandal is the filmmaker’s admission that, while shooting a documentary about Armstrong’s 2009 comeback, he smothered his own innate skepticism; like so many of the athlete’s fans, he wanted a hero more than he wanted the facts.