Episode one of Michael Mosley's three-part series on experimental psychology turns to the darkest branch of the subject: attempts by scientists and governments to control other people's minds. Mosley works through archival footage of Cold War-era experiments designed to break down personality and induce obedience, from academic psychology labs to military and intelligence programs that treated the human mind as a system that could be reverse-engineered and rewired. He sits down with survivors of these experiments, who describe what it felt like to be a subject rather than a researcher, and with the scientists and their descendants who defend or disown the work decades later. The episode does not treat mind control as a conspiracy theory but as a documented research tradition, tracing how techniques developed to understand suggestion and coercion were repeatedly tested on people who had little power to refuse. It sets up the series' larger question: how much of what we call personality turns out to be alterable under the right conditions.