IBM Watson won a million dollars on national television, tried to become a cancer doctor, drifted through a string of odd jobs, and was finally sold for parts. The idea began in 2004, when an IBM manager at a steakhouse saw diners abandon their meals to watch Ken Jennings on his 74 game winning streak. Under principal investigator David Ferrucci, the 2006 prototype answered about 15 percent of clues correctly. The finished machine ran on 90 servers with 16 terabytes of RAM and had to play completely offline.

This episode tells Watson’s story like the biography of a child star. It explains the DeepQA system, in which hundreds of algorithms voted on hypotheses until a confidence score triggered the buzzer, and it revisits the 2011 match against Jennings and Brad Rutter. Then it follows the push into health care with Memorial Sloan Kettering and MD Anderson, where messy medical records defeated a system built for clean text. The verdict offered here is that the engineering was real and the marketing promised far too much.

• Producers made IBM build a mechanical finger to press a physical buzzer, yet Watson could still react in about eight milliseconds.
• Watson could not hear its opponents, so it once repeated the exact wrong answer Ken Jennings had just given.
• In a Final Jeopardy category on US cities, Watson answered Toronto with five question marks when the answer was Chicago, home of O’Hare and Midway.
• The MD Anderson pilot was discontinued after a reported $65 million investment without ever being used on active patients.
• Later assignments included personal shopping for an outdoor clothing brand, recipes like Peruvian potato poutine, and tax deductions, before the health unit was sold to a private equity firm in 2022.