On her last day of work, homicide detective Sarah Linden is drawn into a new case about the disappearance of a teenage girl, Rosie Larsen. Mitch and Stan Larsen frantically try to track down their daughter when they learn she did not show up at school. City Councilman Darren Richmond prepares for an important forum with the Mayor as the election nears.

Sarah and Holder discover more on Rosie, but the investigation gets stalled when they have to set out on a search for Jack.

Sarah and Holder evade the FBI and unearth new evidence. Mitch endangers the boys, prompting Stan to take matters into his own hands. Richmond tries to climb back in the race.

Sarah has her own reasons to join the task force; Holder finds a new street informant; Seward strokes an old rivalry.

The task force shuts down a business; Sarah and Holder unite in their pursuit of "the voice"; Seward is offered motivation to comply with orders.

Bullet races to find a victim on the run before someone else does; Seward is discourteous to surprise visitors.

The investigation into Rosie’s killer begins as Sarah and Holder question the missing girl’s parents, Stan and Mitch, as well as Rosie’s friends and City Councilman Richmond. Rosie’s school becomes a potential murder site when Sarah and Holder uncover shocking evidence on campus. Heartbroken and grief-stricken, Mitch and Stan face the aftermath of losing their daughter.

Councilman Richmond suspects a leak within his team; Sarah tracks down a witness and is led to a suspect.

Linden and Holder pressure Jasper for answers and interview a new suspect.

Rosie's teacher provides Sarah and Holder with a new piece of evidence. Richmond's campaign team plans a new anti-crime television commercial. Mitch continues to struggle with the loss of her daughter, while Stan becomes more determined to find Rosie's killer, and asks his colleague Belko for help.

Sarah and Holder intensify their investigation on a suspect's family and friends. Gwen and Richmond disagree over strategy for the next debate with the mayor. Meanwhile, Rosie's funeral takes place and Stan concentrates on his own investigation into her death.

Mitch questions the validity of the police investigation while Richmond has to deal with a negative ad. It's discovered that Rosie was at Bennett's apartment the night she died.

The police are thwarted in their efforts to arrest Bennet. Richmond thinks long and hard about removing himself from the Mayor's race. Mitch and Stan have had it with the police.

Sarah hunts down Rosie's backpack as Holder falls from grace. Mitch re-emerges while Stan continues to entangle himself with the mob. Richmond faces up to his situation.

Holder and Linden get a break in the case; Seward clashes with death; Bullet becomes a protector.

Richmond rises in the polls; a surprising individual turns himself in.

Sarah zeros in on a Larsen-family secret; Stan comes to grips with some past indiscretions; and Mitch takes in a runaway girl. Meanwhile, the Richmond campaign entertains a surprise visitor.

Sarah makes a grim discovery in regards to her past; Holder catches an unsettling case; Seward shows his true colors.

Linden and Holder catch up to the latest victim; Seward faces his past; Bullet struggles with the truth while in the jungle.

Sarah and Holder identify the mystery man with the tattoo while Jamie attempts to enlist Gwen's help and Stan learns his past may have come back to haunt him.

Sarah receives a message from the dead that may shed light on the identity of Rosie's killer. Meanwhile, Mitch befriends a young runaway; and Richmond has grave doubts about his future in politics.

Sarah teeters on the edge. Stan attempts to make amends. Richmond receives an unexpected boost in the mayoral race.

Sarah makes a grim discovery in regards to her past; Holder catches an unsettling case; Seward shows his true colors.

An ominous discovery is made at the Larsen house while Sarah travels to Tacoma to learn Councilman Richmond's dark secret. Meanwhile, Richmond is forced to come to grips with the fallout from the attack at City Hall.

Sarah seeks peace in the case's aftermath; the detectives pick up an unnerving new assignment; Lyric is tempted by her old life; Danette says good-bye.