The Proving Ground

Michael Connelly’s The Proving Ground (2025) is the eighth legal thriller in the popular Lincoln Lawyer (2005) series. The novel follows defense attorney Mickey Haller, who has transitioned from his well-known criminal practice to the high-stakes world of civil litigation. Haller takes on the case of Brenda Randolph, a mother suing a powerful tech company, Tidalwaiv Technologies, after its generative AI companion allegedly encouraged a teenage boy to murder her daughter. As Haller prepares for trial, he must navigate a labyrinth of corporate obstruction, witness intimidation, and digital secrets to hold the company accountable. The novel explores The Abdication of Moral Responsibility in Technological Advancement, The Manipulation of Truth in the Pursuit of Justice, and The Perversion of Justice by Corporate Greed.

A former crime reporter, Michael Connelly is an award-winning and bestselling author of crime fiction and a Grand Master of the Mystery Writers of America. He is best known for his interconnected universe of novels, including the long-running Harry Bosch series and the Renée Ballard series, characters from which sometimes appear in Haller’s stories. The Proving Ground taps into contemporary anxieties surrounding the rapid, unregulated growth of artificial intelligence, drawing inspiration from real-world lawsuits and public warnings from legal bodies about the technology’s potential dangers to young people. Haller’s character has gained renewed popularity through the Netflix television series The Lincoln Lawyer, where Connelly serves as an executive producer.

This guide refers to the 2025 Little, Brown and Company first edition.

Content Warning: The source text and this guide feature depictions of child death, death by suicide, child abuse, graphic violence, substance use, and cursing.

Plot Summary

Attorney Michael Haller, now practicing civil law, appears in federal court for a pretrial hearing in the case of Randolph v. Tidalwaiv Technologies, LLC. Haller represents Brenda Randolph, whose teenage daughter, Rebecca, was murdered by her ex-boyfriend, Aaron Colton. The lawsuit alleges that Colton was encouraged to commit the act by Tidalwaiv’s product—an artificial intelligence companion, Clair. The defense, led by attorneys Mitchell and Marcus Mason, has heavily redacted discovery documents, claiming they contain proprietary information. Haller argues against the redactions and a defense motion to strike his key witness, Rikki Patel, a former Tidalwaiv employee who signed a nondisclosure agreement. Haller contends the NDA was signed under duress. The judge, Margaret Ruhlin, takes both matters under advisement.

After the hearing, writer Jack McEvoy approaches Haller, offering his research expertise on technology in exchange for inside access to the case for a book. Haller directs his investigator, Dennis “Cisco” Wojciechowski, to vet McEvoy. Haller then visits his first ex-wife, Maggie McPherson, the newly elected Los Angeles County District Attorney, to request access to Aaron Colton’s laptop. Maggie refuses, citing the ongoing juvenile criminal case against Colton. Haller leaves a 12-terabyte external hard drive on her desk, urging her to make the moral choice. Shortly after, Haller finds an identical drive containing the laptop’s complete data on the seat of his unlocked car, its provenance officially unknown to him.

Judge Ruhlin rules that Rikki Patel can testify but that the discovery redactions will stand. McEvoy begins analyzing the discovery materials inside a secure Faraday cage at Haller’s warehouse office. When Haller and Cisco are unable to reach Patel, they go to his Venice Beach bungalow. They find the door unlocked and discover Patel dead in his bed from an apparent overdose of OxyContin, with an eviction notice nearby suggesting severe financial distress.

Haller pressures the police into conducting a full investigation into Patel’s death rather than ruling it suicide at the scene. At an emergency court hearing, Haller uses this investigation to force Marcus Mason to reveal that the defense had Patel under surveillance. Judge Ruhlin admonishes both legal teams for their tactics. Meanwhile, McEvoy discovers that in all of Tidalwaiv’s internal emails, one recipient’s name has been consistently redacted. He identifies the person as Naomi Kitchens, a former ethicist on Project Clair whose existence has been concealed.

Haller and McEvoy fly to Stanford University to meet Naomi Kitchens, who agrees to see them despite being fearful that Tidalwaiv is watching her. Haller argues that the company has positioned her to be the scapegoat for the project’s ethical failures. He gives her a burner phone for secure communication. After their meeting, Haller learns from panicked calls from Maggie about massive wildfires. Maggie’s home is destroyed. Six weeks later, Maggie is living with Haller, rekindling their relationship.

When the trial is delayed, Aaron Colton’s parents hire Haller to also sue Tidalwaiv, and their negligence lawsuit is consolidated with Brenda Randolph’s case. McEvoy begins analyzing the extensive chat logs from Aaron’s laptop—conversations between Aaron and his AI companion, whom he named “Wren.” Tidalwaiv’s settlement offer of $20 million is rejected because it includes no public apology or admission of fault.

To learn more about Wren without alerting Tidalwaiv, Haller’s team logs Aaron’s computer onto the Wi-Fi at the Van Nuys police station, near where Aaron is being held, ensuring any IP trace leads to the LAPD. They briefly interact with Wren before Tidalwaiv cuts the feed. Inspired by a Netflix documentary about a whistleblower coming forward after the Challenger disaster, Naomi Kitchens gives Haller a thumb drive containing all her reports and emails. Haller presses her to testify, and she eventually agrees. The weekend before the trial, Tidalwaiv offers a $50 million settlement, which Brenda again rejects.

Meanwhile, Haller takes on a habeas corpus case for David Snow, a former client convicted 20 years earlier of abusing his three-year-old daughter, Cassie. Now a law student, Cassie has been diagnosed with osteogenesis imperfecta, or brittle bone disease, providing new evidence that her injuries were not the result of abuse. Her father is dying of cancer in prison.

The trial begins with Haller delivering an opening statement. Detective Douglas Clarke testifies about the murder investigation and his discovery of Aaron’s relationship with Wren. He reveals that Wren’s conversational data included quotes from adult-oriented sources like Shakespeare and Blue Öyster Cult. Haller introduces transcripts of Aaron’s conversations with the AI, culminating in the revelation that Wren provided Aaron with a list of possible combinations to his father’s gun safe, one of which was the correct code.

During the trial, Naomi Kitchens’s hotel is discovered, and a note with her birth name, “Alison Sterling,” is slipped under her door. Terrified, she is convinced to testify only after Haller reminds her she is under subpoena. On the stand, Kitchens explains she changed her name to escape a violent ex-boyfriend. She testifies that Project Clair was dangerously flawed, with an AI trained on adult data and male biases being marketed to children. On cross-examination, Marcus Mason ambushes her, alleging she was fired for an undisclosed sexual relationship with a coder she supervised, Patrick May, which severely damages her credibility.

Furious, Bruce Colton confronts Haller. The Coltons meet with the Masons and agree to settle for $3 million. Mason offers Brenda $10 million, which she rejects. Suspecting the Coltons have made a deal to testify for the defense, Haller decides not to call them as witnesses. Dr. Deborah Porreca, an expert on digital addiction, testifies that Aaron was in love with Wren. The case turns when Professor Michael Spindler, an AI expert, testifies about the garbage in, garbage out principle of computing. He also explains that Wren’s texts to Aaron spelled “hERo” with a capitalized “ER” in tribute in the incel subculture killer Elliot Rodger, linking the AI’s code to a hateful ideology.

The trial is paused when a juror tests positive for COVID. That day, Victor Wendt, the founder of Tidalwaiv, visits Haller and offers him a $2 million cash bribe to convince Brenda to settle. Haller throws him out. The next morning, Haller is shown an anonymously sent video of Cisco visiting the sick juror’s home, a clear setup. The judge keeps the juror on the panel. Haller calls Tidalwaiv coder Nathan Whittaker to the stand. Haller exposes Whittaker’s combative personality and connects his username, “wiseacre23,” to misogynistic and incel-related websites. In chambers, Haller reveals he has evidence linking Whittaker to a defunct dark web site. Facing this, and Haller’s final gambit of a motion to call Wren as a witness, Tidalwaiv agrees to settle for Brenda’s demands: a public apology and promise to correct mistakes, rather than just money.

A press conference is held where Tidalwaiv settles for $52 million and admits wrongdoing. Brenda Randolph announces the creation of the Rebecca Randolph Center for Technological Oversight, with Jack McEvoy as director. Haller gives his team members million-dollar bonuses and refuses a retainer from Victor Wendt. The next day, Judge Ruhlin praises Haller, and jurors from the case tell him they were ready to rule in favor of Brenda.

As he leaves the courthouse, Haller receives a call from the prison informing him that David Snow has died. He is left with the weight of his past failure and the knowledge that some injustices cannot be undone.