Season 4

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 René 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 fiancée 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.