An alliance between a detective and a criminal create deadly consequences.
The investigation of a police officer's murder shows he is allied with a notorious criminal.
The officers must investigate the murders and rapes of new mothers.
A shooting at a dance club leads to a family being murdered.
The discovery of a a buried skeleton reopens a 25 year old mystery.
Bodies of women are found in a warehouse.
Mistaken indentity is the probable cause of a drive-by shooting.
The officers must investigate the death of a student who was found in a subway station.
The Russian Mafia is suspected of a celebrity's shooting.
The officers discover that mysterious deaths at a hospital may be somehow linked with unsolved deaths.
A racial killing is suspected when a black civilian is shot.
Four abortionists are killed and the killer's next target is posted on a website.
The investigators must find some link between an anti-abortionist group and the murders of abortionists.
The officers must investigate an assault on two women.
A psychiatrist is found murdered at a criminally insane hospital.
A failed bank heist brings low police morale to the surface.
When a politician and his wife are found dead, the squad initially suspects that it may be a murder/suicide.
The police investigate a crime-suspected adoption company.
The homeless living on the streets are the target of a murderer.
A connection is found between a biker's murder and a mobster's murder.
Four accountants are murdered, and the investigation leads to a maze of possible murderers.
Oosterhius is convicted of a murder.
Castillo and Sweet try to track down some kidnappers that have given the team 36 hours before they rape the kidnapped child.
Sweet and Castillo investigate the racially motive package bombs that kill Carlotta Alcantara and Martin Simpson, and find themselves dealing with a suspect who ignores Sweet because he's black and is equally dismissive of the Hispanic Castillo. It isn't long before they realise Carl Purdy's motive is connected to his ex-wife's new Cuban husband. Pogue and Oosterhuis investigate the death of political intern Tammy Moore, who was found hanged and dressed in bondage gear by an underpass. Their investigation leads them to the Club de Sade, whose owner sends them right back to the lawyer who had sworn Tammy was too freaky for him.
A raped woman is found in an abandoned building, and the pattern looks like a crime that Castillo once failed to solve.
After the serial rapist is found murdered and evidence shows he was killed by a woman, Castillo and the rape victims are prime suspects.
The squad gets involved when a shoot-out in a market leaves a popular officer paralyzed from the waist down. It doesn't take long before they realise that a bounty hunter is after the men in question, all of whom seem to be on the run from various conviction threats in the U.S.
Pogue and Oosterhuis investigate when a young girl named Erica Warner is taken from in front of a local store, with her older sister Shannon as the only witness. While Oosterhuis questions Shannon, he can't help but see similarities between the two of them, because when he was 13 he once lost track of his little brother at a carnival for a few hours and felt responsible for years. The squad soon realises that Erica's disappearance as a lot in common with that of a young girl who disappeared three years earlier, and they're determined to find Erica and stop the kidnapper before he can take another young girl from her home.
When Amber Watley calls to report the body of a young man by the tracks, the squad immediately moves in to investigate, but it doesn't take long before Weeks and Gillam realise that there is no way it happened the way that she said it did. As the squad continues to investigate the death of Donnie Tenio, they soon discover that the problems in the group of teens go far deeper than they could have imagined.
A man is found in a parking garage, beaten and amnesiac, with only a book of bird drawings to identify him. Pogue takes the book to his wife Carolyn in the hopes that she can identify the birds and narrow down where the man is from, and in exchange for her helping, Pogue ends up having to spend a great deal of time looking after their daughter Cara, much to Oosterhuis' frustration. While Weeks and Gillam focus on dealing with the patient, who has taken a shine to Gillam, they soon locate his wife, only to learn she's not the only Mrs. John Doe.
When the body of a male escort is found, Pogue and Oosterhuis get the call. Initially confused as to why they're called in, the reporting officer reveals that Barrow's business card was found on the body. While investigating the crime and trying to clear their boss, Pogue and Oosterhuis soon realise that the man's death had less to do with his profession and more to do with a pending legal action against a former employer. Gillam thinks she has finally found her Mr. Right in Christian, a former high-school classmate, but Weeks is immediately suspicious of Chris, and when doing a background check, Weeks ends up getting himself beaten by thugs who are pressuring Chris to get information from Gillam.
Fourteen years earlier, a fifteen-year-old girl named Alicia Turner was murdered, and a seventeen-year-old named Nick Randall was convicted of her murder. When Tommy Granato claims Randall is innocent, Barrow asks the team to take a look into the investigation because that was her first major case. The squad soon nabs a three-time loser named Al Snedden who points them to his former cellmate Wally Maestre, swearing that he confessed to the murder. When Snedden gives the squad information that only the killer could know, the squad turns all their eyes on Maestre, yet his sister Bonnie provides him with an iron-clad alibi.
When pretty blonde Patsy Grady is found dead in the passenger seat of her husband's car, the squad initially can't figure out any possible reason why someone would kill the young woman, but as they investigate the case, the squad realises that Patsy was not only unfaithful to her husband, the paternity of her child was in question. This leads them to playboy Malcolm Harding, who is quick to point out that he has no reason to kill Patsy because he had a vasectomy. Meanwhile, Pogue and Oosterhuis investigate when Carolyn reports that there has been a man calling her and making obscene threats for the last few weeks. Oosterhuis tries to convince Pogue to back off, but he's determined to fix the problem, even if it means spending more time than he should with Carolyn.
Cisco Powell, Steff Marable, Robbie Testanie and Sammy Ackerman are the four heart throbs of the pop band Angel Force until Sammy is found dead, assumed to have jumped out of the penthouse loft he and the other members were staying in. When Thorpe shows the squad that it couldn't possibly be suicide, Pogue and Oosterhuis investigate the murder with the other bandmembers while Weeks and Gillam talk to the people who met the band members. Pogue's got more problems, though, when Carolyn comes to him and tells him that she thinks she's pregnant, and the child is his.
When diamond courier David Ramsey is found burned to death with his hands barb-wired behind his back and a tire around his body, Oosterhuis realises that he is killed in a traditional South African style, and he and Pogue wonder if someone was trying to send a message. Weeks and Gillam investigate the death of a small child who shows a history of physical abuse when their medical examiner tells them that he disagrees with the coroner's report that the mother caused the child's death, especially considering the child wasn't even with the mother when the fatal blow was struck.
When Blair Patterson's beheaded body is found in a van that's been sitting in a neighborhood for days, his wife turns the squad onto Emily Glover, a tenant in the apartment building Blair managed, who immediately confesses to his murder and claims she and Blair were killing couples throughout the city. When another couple is found dead in the same way as the others, the squad realises that something with Emily's story is off, and it's up to Oosterhuis to try to get it out of her as Emily will not talk to a female detective, and has already given up on Weeks.
Oosterhuis and Stahl investigate the death of Filippino nanny Rhodoura Santos, whose employers hadn't even realised she was missing. The Vucetas swear that Rhodoura was about to be fired because she wasn't a very good nanny, but in talking to other nannies in the park, Stahl and Oosterhuis get a whole different view of things. Weeks and Bender investigate the shooting of Alan Rotteirs, the director of a local youth center, who had announced his plans to clean up the community, in particular to get rid of local tough Bobby Fuentes.
When construction company owner Richard Marr goes missing, the squad is brought in by his devastated wife Peggy, but the squad soon learns that Marr was a child molester who faked his own disappearance to get away from the angry parents of his victims and the criminal charges associated with it. Forensics specialist Roberta Thorpe asks Ed to prove the innocence of her young colleague Noel Watson in the death of his wife, but she ends up coming under suspicion herself.
The squad is called in to investigate the death of Detective Sergeant John Van Impe, and are soon faced with two suspects -- the officer's younger partner, Wayne Tocchet, and a long-time informant who fled the scene, Marlon Cummins. As the investigation continues, the squad begins to realise that they may have to arrest one of their own.
When two women with the same name are murdered within days of each other, Weeks and Bender can't agree on whether or not the two deaths are related. Oosterhuis' new partner, Stahl, worries about Oosterhuis' relationship with teenager Jamie. Oosterhuis believes Jamie is troubled, Stahl thinks she's just plain trouble.
The squad investigates the murder of a teenage boy at a local private school, and soon realise that there were many students in the school who had a very good reason to want him dead.
When Sheila McBride, the ex-wife of crime reporter turned best-selling novelist Cam McBride, is found dead in her home, it is initially thought to have been the work of a burgler. When the squad learns that she had recently won a substantially large added settlement from her ex, suspicion turns on him. Ronnie has trouble keeping herself objective since she and Cam were former lovers.
When a woman comes forward claiming to be a psychic who witnessed a murder, she is the squad's first suspect, until someone else is killed.
When a young woman named Julie Hagen is found dead, everyone in the house becomes a suspect, and Weeks doesn't endear himself to the cook and her brother, who believe that Weeks is harder on them because they're black.
When math professor Nathan Cuthbert is found dead, Oosterhuis and Stahl investigate, and Oosterhuis is soon warned off the case by Colin Gladden, his former partner when he first started with homicide. Unfortunately, Oosterhuis disappears during the investigation. Bender and Weeks investigate the suspicious death of journalist RenÃ© Cloutier, who was found hanging in a closet wearing women's clothing. While investigating Cloutier's death, which turns out to be the result of poisoning, Lukowich tells Bender and Weeks that Cloutier was killed by the same poisoned drug as Stahl and Oosterhuis' victim.
When actor Lordan James is found murdered in his trailer Oosterhuis and Stahl investigate, while Weeks and Bender babysit Weeks' son Tyrone at the station while doing background checks.
Bender and Weeks investigate the death of Norah Mavrin, a high-ranking provincial cabinet minister. At first they think that dirty dealings and backroom bargains are the reason she died, but they soon learn that Norah, a married woman, had no shortage of adulterous lovers on the side, which turns suspicion to her husband Owen. Barrow sends Oosterhuis and Stahl to escort killer Bernie Frank from New York, where he was apprehended by retired staff sergeant Ross Entwhistle, to Canada to stand trial. What they find, though, is an elderly man with early on-set Alzheimers who just wants 'to go home'.
When the mummified remains of an infant are found inside a tree, Weeks and Bender investigate the former residents of the house and learn that the baby was never registered, and the suspects include the mother, who is completely out of touch with reality, and her husband, an ex-convict who is not the baby's father. Ed's former fiancÃ©e Marissa calls him in for help when her parents disappear, but it's only a matter of time before Stahl and Oosterhuis discover that Marissa's parents are involved in an elaborate con to bilk people out of their hard-earned money.