David awakens from a blackout to find blood and a smashed headlight on his car, and panics when he hears about a late-night hit-and-run; Tom and Ray respond to a possible kidnapping, only to find an elderly Alzheimers patient tied to a bed; as David tries to reconstruct the events of the night before, he raises the suspicions of Joel, Fearless and Ray, whose investigative abilities find the common link between the two cases.

Joel and David face off over negotiating with armed robbers who have taken hostages during the heist of a sporting goods store; stung when he fails to get a promotion based on not ""stepping up"", Ray insists upon going undercover as a paramedic to scope out the situation inside the store; after being recognized as a cop by one of the perps, Ray is beaten, tied up and threatened with death and must convince the store manager, a former actor who once played a cop on TV, to step up to the plate and resist the gunmen; when one of the robbers forces Ray to have a last telephone conversation with his wife, Ray calls Tom instead and gives him the information the swat team snipers need to end the standoff; in the aftermath, Ray discovers an unpleasant truth about the store manager, whose television character inspired Ray to become a cop.

Fearless faces demons from his past as he investigates the shooting death of a small-time drug dealer.

The circumstances leading to the murder of a teenager and the wounding of a little girl in a drive-by shooting unwind from the points of view of the deputy district attorney, police, paramedics and reporters who report to the scene, and finally, that of one of the perpetrators and his grandfather. David McNorris, the deputy district attorney, manipulates the tragedy to feed his insatiable appetite for power, prestige, and media exposure. Detectives Joel Stevens and Bobby ""Fearless"" Smith and Officers Ray Hechler and Tom Turcotte encounter protective parents, traffic accidents, and a near-drowning as they investigate the shooting and track down the teenaged suspects. Paramedic Teresa Ortiz tends to the wounded young girl and provides the detectives with the information they need to solve the case. Reporter Andrea Little flirts with danger as she strikes up a conversation with her lover's wife to get one scoop on the story, and shows humanity when she refuses to capitalize on a man's gri

During a search for a kidnapped newborn, Joel and Fearless uncover an obstetrician's plot to steal the babies of recovering addicts; on the eve of entering rehab, David gives Joel the heads-up that IAB is reopening the investigation into Emma's death; Tom takes the upper hand and neutralizes Trumper's attempt to coerce him into snitching on Joel; Kelly and Joel discover that although they each feel guilty for the death of their daughter, there was nothing they could have done to save Emma from the cerebral aneurysm that ended her life.

Joel and Fearless solve the 26-year-old cold case of the murder of Paul Turcotte's partner during a bank robbery, forcing Tom to relive his childhood memories of the shooting and the effect it had on his father, and validating Andrea's five year struggle to free the unwitting accomplice originally convicted for the slaying.

A powerful Hollywood producer offers to advance David's career in exchange for David's obstructing justice to protect the producer's teenage son who's accused of the murder of a teenager; Joel and Fearless uncover the painful family secret which led to the girl's murder; after David confesses his affair with Andrea, Marian leaves him.

Investigating the brutal murder of a homeless man bludgeoned to death with a brick, Joel and Fearless follow up on a tip from Teresa and discover two filmmakers who pay vagrants to become would-be gladiators and battle each other in the park; when the detectives realize that the filmmakers bribed a homeless drunk to land the fatal blows, they team up with Tom and David in the search for evidence to convict them.

Joel and Fearless search for killers who prey on unsuspecting families in their sleep and stake out the family that they believe to be the next target; when Andrea's reporting skills threaten their investigation, the detectives are forced to give her a front row seat to their trap.

When he responds to a burglary call, Ray finds two cops murdered in an apparent ambush, and discovers that the shooters were tipped off by someone within the precinct; the FBI locks down the station, leaving Joel to uncover the mole; despite Andrea's nearly costing him his badge a year earlier, Ray enlists her help in tracking down the perps.

Joel and Fearless, and Ray and Tom, discover that things are not what they seem as they set off in a high speed pursuit of a man who is overheard by a telemarketer murdering one person and planning to kill another; as he arranges several meetings with Andrea, David works overtime to allay his wife's suspicion that he's having an affair.

Joel and Fearless work with a claims investigator, who is also Fearless's ex-girlfriend, to uncover the insurance fraud ring behind a fatal multi-car collision.

Teresa's ambulance is hijacked by a thief who threatens to kill her if she doesn't save his brother, who's been shot in the heart during a burglary; Ray and Tom go undercover to track down a trio of larcenous pranksters, who get the scare of a lifetime when they're captured; David has a horrifying time at a Hollywood Halloween party when Andrea breaks off their relationship and Marian accuses him of adultery.

Haunted by a promise he made to an old friend, Fearless risks his life to protect a little girl who is the only cooperating witness to a mob hit; Ray and Tom investigate a stolen corpse that was shot through a cannon and landed in a hot tub.

Joel and Fearless enlist the help of Andrea and a psychiatrist in obtaining information about the kidnapping of a teenager from the only witness to the crime, a psychotic homeless man who was Andrea's friend in high school.

In the hours before his execution, a gangbanger gives McNorris a last-minute ultimatum to either save his life or risk the death of a cop kidnapped by his cohorts; Ray's contacts on the street lead the police to the location where the officer is being held, but they arrive too late to save their fellow officer.

When the charges against Robert Colson, a prominent attorney accused of murdering his former girlfriend, are dismissed at a preliminary hearing, the detectives and patrol officers look for ways to put pressure on Colson's brother and his family to get one of them to flip on him; Andrea takes a personal interest in the story, which keeps David's name on the front page and causes friction with her mother; Joel, who also has taken the case to heart, risks his life as he obtains the evidence that will close the case legitimately after he disagrees with Ray's planting evidence against Colson's sister-in-law to use as leverage.

Responding to a domestic disturbance call, Ray and Tom find themselves in the middle of a homicide investigation as their feuding couple is linked to a fatal meth lab explosion; when the husband has his throat cut outside of the police station, their drug dealer becomes the prime suspect.

Joel and Fearless enlist Ray and Tom in an covert op to track down the thieves who killed Wisnicki and Chandler when the detectives assigned to the case fail to go after John Donadoni, the man behind the murders; when tailing Donadoni leads to Sabrina Fithian, Joel and Fearless break into her apartment to wire it, and stumble into a surveillance led by Katherine Pierce, a Robbery/Homicide detective who's been after Sabrina, and knows that Sabrina and her partner Rachel are the cop killers they're after; after Donadoni threatens Kelly and Willy, Joel lets Donadoni know that Donadoni's mother can also find herself in danger; at Joel's urging, Katherine gets herself reassigned to their squad and gets Ron to assign them to her task force; Sabrina is captured after the team interrupts her latest burglary, but not before Sabrina wounds Katherine and then shoots a two-timing Rachel with Katherine's gun; Joel warns Donadoni that he's a marked man, no matter what happens to the case against S

David comes out of rehab and lands in the middle of the case against Sabrina and Donadoni, although not in the position he'd like at first; Ray and Katherine get bloodied on the witness stand at the preliminary hearing by Sabrina's attorney; David's struggle to stay sober is sorely tested when his father comes for a visit bearing extremely troubling news; when the diamonds stolen by Sabrina and Rachel can't be found, the task force puts their heads together with David to recover the gems, find the key to getting Sabrina to do a full flip on Donadoni, and put Donadoni behind bars.

Called to the police academy to investigate a murder, Joel and Fearless discover that the recruit who discovered the body is none other than Teresa; Ray and Tom work with Katherine to stop a ring of thieves posing as police officers.

Bank robbers attempting to flee the scene end up at a local shopping mall and take several hostages, including Teresa, whose ""shoot, don't shoot"" lessons at the academy come in handily at a critical moment.

When the body of a college student is found in a house under renovation, David joins forces with Katherine, Joel, and Fearless to determine which of the victim's frat brothers is responsible for his demise and burial in the wall of their former frat house twenty years earlier.

Wracked with guilt for not following his instincts on a domestic disturbance call when the woman involved is reported missing and presumed dead several hours later, Tom works with Katherine to uncover the whereabouts of the woman and the person who murdered the chief suspect in her disappearance.