"The Poet," by Michael Connelly, begins with Denver news reporter Jack McEvoy being informed that his twin brother Sean is dead. Sean was a member of the Crimes Against Persons Unit (CAPs) in the Denver Police Department. According to two of Sean's men, Harold Wexler and Ray St. Louis, Sean committed suicide while parked in his car at Bear Lake.

Although Jack and Sean were twins, they hadn't spoken much in the last few months. The brothers had had an argument about the Theresa Lofton case, Sean's obsession and the elusive topic of a story for Jack. In general the brothers' relationship was good and Jack takes the death hard. As a result, Jack decides to write about Sean's death and never fully believes that it was a suicide.

Jack begins to conduct a lengthy investigation that takes him to places he never would have dreamed of going. Several facts about Sean's case are suspect and Jack believes Sean was murdered. As Jack's theories begin to pan out, Sean's old partner realizes that Jack is right. Sean McEvoy was murdered.

The case leads Jack to investigate other police murders intended to appear as suicides. The main link seems to be cryptic notes left at the crime scenes. Each is taken from a quote from Edgar Allan Poe; most are from poems and stories while one that does not seem to fit is actually the quote of Poe's last words.

As the investigation heats up, Jack becomes involved in the FBI's investigation of the serial killer referred to as the Poet. Jack is quickly pushed to the side until he convinces the FBI team leader that he has information that the agency needs in order to solve the case. Jack and the team leader, Bob Backus, make a deal - Jack's information for an exclusive story.

Jack meets Rachael Walling, the lead agent on the case, and the two quickly become involved in an intimate relationship. The relationship is both good and bad for both, the bad part being that it clouds Jack's judgment regarding the facts.

The case takes Jack to Quantico, Phoenix and LA as the trail of pedophile William Gladden heats up. It is clear that the elusive Gladden is responsible for the murders of the children but the killing of the cops is not yet clear.

Along the way, a pedophile network is uncovered. Jack makes friends with a former reporter who sets him up and steals the story for a front page byline in the LA Times.

Jack and Rachel's ex-husband Gordon Thorson develop instant animosity and Jack believes that Thorson has been leaking information to the press.

The story accelerates when Gladden is located and a sting is set up to capture him. In the melee, Thorson is killed. Jack tries to get Gladden to confess but there is something off about the man's comments. Gladden manages to shoot himself while Jack holds the gun.

After Gladden's death, Jack begins to realize that while he was responsible for the children's murders, Gladden was not the poet. Jack begins to thread together facts that lead directly to Rachel as being the Poet. Jack fights against the facts but finally cannot deny it and reports it to Backus. Backus supposedly sets up a sting but when Jack is taken to a secure location, Backus confesses that he is the Poet and drugs Jack with the intention of molesting him and then killing him. Rachel appears and shoots Backus, who manages to get away.

The relationship between Jack and Rachel seems to be irreparably damaged. Backus' body is found but there is no proof that the body is really his and Jack and the agents know that Backus will return someday.

Jack stays in LA after the case is closed. Jack writes a book and hopes that Rachel will return while trying to ward off the nightmares from his contact with evil.