Jamie goes under cover with a deadly human trafficking ring; Danny and Baez investigate a homicide connected to Darryl Reid, Danny's old partner; Frank grapples with whether to publicly support Mayor Chase on a policy decision.
Danny and Baez join forces with Danny's old partner when a serial killer reappears; Eddie faces backlash when she tries to help a woman who accuses a sergeant of rape; Jamie clashes with his nephew.
Franks struggles with grief over his best friend's death. He attempts to aid the friend's jailed daughter, Tess Ross. Meanwhile, Jaime and nephew Joe hurry to reunite a trafficking survivor with family.
Danny reunites with a troublesome teenager from a past case when the youth finds herself in danger; Frank faces a difficult personnel decision; Jamie grows suspicious when Henry is asked to be interviewed for an investigative web series.
Erin is designated to lead a federal investigation into corrupt horse racing; Jamie investigates a drug trafficking operation involving rival gangs; Danny and Baez look into a series of assaults in Little Vietnam.
Danny and Baez investigate a homicide involving voodoo with the help of Baez's old partner; Eddie and a fellow officer team up with Capt. McNichols when they suspect a prestigious school is employing discriminatory admission practices.
Jamie works to bust scammers who are defrauding the elderly; Danny and Baez investigate a series of mysterious deaths at a hospital; Anthony is determined to take down an attorney who exploits the law for his own financial gain.
Danny and Baez are on edge when Sam Evans, a serial killer who once targeted Baez and her daughter, is released early from prison; Jamie and Anthony team up on an investigation involving one of Anthony's criminal informants.
Danny gets involved when Sean becomes the latest victim in a series of robberies on Sean's college campus; Erin grows suspicious of an overworked attorney who she believes isn't acting in his client's best interest.
Danny and Gormley pursue Gus Vanderlip, an ex-detective determined to uncover how a rapist he caught is free. Concurrently, Jamie and Eddie go undercover as their anniversary nears.