While off duty, Grace chases down a subject who turns out to be one of the FBI’s Most Wanted. Afterwards, she is hailed a hero. But nobody is aware of what she was really doing on her day off, a shocking secret involving the priest who molested her as a child.
Grace is called to a crime scene that happens to be the home of Paul Shapiro, whose father died in the bombing of the Murrah Federal Building. Since then, Paul has been in and out of trouble. At the crime scene, there is blood everywhere, but no body. Ham has separated from his wife and moved out on his own, giving him and Grace more freedom to be together. They wind up in a ketchup-and-mustard situation that soon becomes a running joke in the squad room.
Ed Ligardi, who serves as evidence supervisor for the squad, turns up dead in a bathroom stall at Louie’s, the local cop hang-out. And it just so happens Grace and Ham are fooling around in a stall just five feet away when the murder happens. But the case takes an even more bizarre turn when the prime suspect offers up a rather strange confession. Also, Ham’s brother, Ralph, comes to visit before being shipped off to war. And Grace has a strange dream about Leon Cooley, who turns out to be having dreams about Grace.
An impending divorce, a gambling habit, a young boy acting out and a teenage girl dating a rebellious stoner set the stage for tragedy when the mother of two children goes missing for several days. Clay, Grace’s nephew, joins the OCPD Explorers program against his father’s wishes and confronts Ham about his affair with Grace. And Butch becomes the target of a possible stalker who also happens to work closely with the police department.
The door to Grace’s Porsche gets knocked off when a drunk driver slams into it, the impact letting loose thousands of dollars in cash that had been hidden by a previous owner. Among the owners questioned is legendary Oklahoma and Dallas Cowboys football coach Barry Switzer, guest-starring as himself. The investigation eventually entails a murdered highway patrol officer and a wealthy developer. Meanwhile, Ham’s little brother Ralph disappears in Afghanistan hitting the entire squad firmly in the gut. And Ham’s older brother, Nick, expresses strong disapproval of Grace just as Ham decides it’s time to ask her out on a real date.
The squad investigates the brutal murder of a woman and the abduction of her son, a case that has everyone on edge. They work frantically around the clock to locate the boy before any harm comes to him. When they finally find him, it’s everything they can do to keep their passionate feelings about the case in check. Ham has an especially difficult time controlling himself as he continues to struggle with his personal loss.
The death of a young Mexican woman, who is dropped off at the hospital by a known white supremacist, has political implications that could derail a legislative vote on illegal immigration. Bobby goes undercover, which takes the entire squad – and his own wife and family – by surprise. And Ham continues to struggle with a family tragedy.
The squad jumps into action when the victims of an apparent serial killer begin turning up throughout the region. Ham is temporarily partnered with Butch while Bobby is on an undercover assignment. And Grace is paired with Abby Charles (special guest star Christina Ricci), a uniform cop and single mother making a rotation through the squad. Meanwhile, as Leon Cooley’s execution date rapidly approaches, Earl tries to persuade Grace to find someway to help him before it’s too late.
Grace’s niece, Sayre, is arrested after attending a drug-laced scavenger party. The teens run into trouble after raiding their parents’ medicine cabinets, then mixing different drugs. When the squad tries to figure out what combination landed Sayre’s best friend in a coma, they discover that some of the drugs contained a potentially deadly substance. Grace’s temporary partner, Abby (special guest star Christina Ricci), proves herself quite resourceful in getting good leads on the case. But she doesn’t know everything, and Grace isn’t about to let her forget that fact.
While the squad investigates the death of a drug dealer at an apartment complex, Ham and Butch run into Bobby, who is still undercover. The cold shoulder Abby (special guest star Christina Ricci) receives from her fellow officers leads Grace to dig up some information about why Abby was placed with the squad. And Rhetta and Johnny try to build a clemency case for Leon Cooley, but he’s less than willing to participate.
The death of a woman in the home of a well-known architect (guest star Elias Koteas) opens Grace’s eyes to a new world. Meanwhile, Ham is thrilled to be partnered up with Grace again and hopes it will also mean rekindling their romantic involvement. Also, Bobby's undercover assignment comes to an explosive end. Clay has a new friend who is also helping out at the police station (Lost’s Malcolm David Kelley). And Leon Cooley struggles to find his lost faith.
Grace’s brother-in-law Doug starts dating Maggie (special guest star Kathy Baker), a new bartender at Louie’s. But Grace is concerned about how Clay is going to take the news that his father is dating again. Meanwhile, the squad investigates the murder of a jogger with a complicated love life. And Leon gets a blast from the past when one of his former high school classmates pays a visit.
Doug’s relationship with Maggie (special guest star Kathy Baker) kicks into high gear, with a wedding date already set. But their plans hit a snag when Maggie is attacked by an unknown assailant at Louie’s. Leon Cooley’s execution date is just around the corner, and Johnny and Rhetta are desperately trying to save him through a letter-writing campaign. Clay decides to join in the efforts after he befriends Leon’s son, Ben (Lost’s Malcolm David Kelley). But a video surfaces that may destroy their chances.
As the squad investigates a fatal shooting by an elderly woman, Leon Cooley’s execution date arrives. Grace, who has discovered that Leon once helped her sister and was invited to a family birthday party, struggles with whether or not to lend a hand towards stopping the execution. Grace also finds a connection with a young woman, who may also be getting visits from Earl. And Ham’s divorce is finalized, which he hopes will make things between him and Grace more permanent.