The mathematician explores the link between a controversial AI algorithm and Luigi Mangione, the man accused of killing UnitedHealthcare CEO Brian Thompson. There were allegations the company used artificial intelligence to deny insurance claims from vulnerable patients, while Mangione himself studied AI at university. Hannah travels to the US to meet a woman who lost her husband and claims it happened after he was denied healthcare by an algorithm, and she also speaks to a UnitedHealthcare insider who reveals her concerns about their use of AI