The Proving Ground is a legal thriller by #1 New York Times bestselling author Michael Connelly, the eighth novel in the Lincoln Lawyer series featuring defense attorney Mickey Haller. Published October 21, 2025, this 400-page hardcover from Little, Brown and Company (Hachette Book Group) takes on one of the most pressing issues of the modern era: artificial intelligence liability and the unregulated chatbot industry.

Following his "resurrection walk" and need for a new direction, Mickey Haller turns to public interest litigation, filing a civil lawsuit against an AI company whose chatbot told a sixteen-year-old boy that it was acceptable to kill his ex-girlfriend for her disloyalty. Representing the victim's family, Haller's case exposes the lack of training guardrails in the exploding AI business, with billions of dollars at stake and shadowy opposition at every turn. Along the way, he enlists journalist Jack McEvoy to sift through mountains of discovery materials, and McEvoy's dogged digging ultimately surfaces a whistleblower who holds the key to the case.

Praised by the Wall Street Journal, Tampa Bay Times, and Book Reporter as a triumph of courtroom drama and a story ripped straight from today's headlines, The Proving Ground is part of a series that has sold more than eighty-nine million copies worldwide. Michael Connelly is also the executive producer of the hit television series The Lincoln Lawyer. The hardcover edition retails for $32.00 and is also available as an eBook, audiobook, trade paperback, and large-print edition.