Kat and Lock Books in Order

Widowed detective Kat Frank is paired with an artificial intelligence called Lock to investigate missing-person cold cases. When the inquiries become urgent and personal, her instinctive methods must work alongside his logic to save lives.

Kat Frank and her AI partner Lock investigate a man found crucified on a hill. A second killing suggests a serial murderer, but efforts to warn potential victims provoke public hostility and complicate their first active case together.

Detective Kat Frank and her artificial intelligence partner Lock return for another criminal investigation, continuing their uneasy collaboration between human instinct and machine logic.