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.

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.

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.

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 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

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.