In the spring of 1934, Detective Nick Posh has a killer case in his sights - the kind that can enhance his career. But when he's unexpectedly named a material witness in a twice-dismissed murder trial in the central western city of El Reno, Oklahoma, he's forced to choose: walk away from his investigation to testify, or let an innocent man hang.

The court wants Posh as Amicus Curiae - an impartial, yet crucial voice for justice; a friend of the court. The job requires him to be in the field, chasing leads wherever possible; they won't wait. The prosecution is counting on him to remain silent.