Corporate hierarchies get tested against a clinical checklist: no guilt, no remorse, a willingness to use anyone, including a spouse, to reach a goal. The film follows that definition upward through business and politics, arguing that psychopathic traits turn up in leadership at rates far above the general population, and it takes its title from an old saying about fish rotting from the head down. Philip Zimbardo, drawing on decades of research into human behavior, appears to make a different point: most people are not malicious, just passive, unwilling to intervene when they see wrongdoing, though a single person who resists injustice can prompt others to do the same. The film also separates psychopaths from sociopaths, noting that medication can push a sociopath toward psychopathic detachment rather than empathy. Interviews with psychologists and researchers carry the argument, building toward an uncomfortable conclusion: the qualities that make someone dangerous to work for are often the same ones that get them promoted.