Following his 'resurrection walk' and need for a new direction, Mickey Haller turns to public interest litigation, filing a civil lawsuit against an artificial intelligence company whose chatbot told a sixteen-year-old boy that it was okay for him to kill his ex-girlfriend for her disloyalty.

Representing the victim's family, Mickey's case explores the mostly unregulated and exploding AI business and the lack of training guardrails. Along the way he joins up with a journalist named Jack McEvoy, who wants to be a fly on the wall during the trial in order to write a book about it. But Mickey puts him to work going through the mountain of printed discovery materials in the case. McEvoy's digging ultimately delivers the key witness, a whistleblower who has been too afraid to speak up. The case is fraught with danger because billions are at stake.

It is said that machines became smarter than humans on the day in 1997 that IBM's Deep Blue defeated chess master Garry Kasparov with a gambit called 'the knight's sacrifice'. Haller will take a similar gambit in court to defeat the mega forces of the AI industry lined up against him and his clients.