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.

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.

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.

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.

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

The police connect Rosie to a suspicious website. Stan faces his demons while Mitch learns secrets she never knew about Rosie.

The identification of the mysterious Orpheus provides a vital connection to the case. Mitch and Stan reflect on the past while contemplating their family's future.

In the aftermath of the shooting at City Hall and Linden's discovery that the photo leading to Councilman Darren Richmond's arrest was forged, Sarah returns to Seattle to investigate a possible cover up and wonders if she can trust her partner.

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 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.

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 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.

The investigation refocuses on the casino; Stan has an uneasy face-to-face with Richmond; tension grips the Larsen house.

Holder disappears and a desperate Sarah goes looking for him; Stan decides to take matters into his own hands; and Richmond returns to City Hall.

Richmond lends support to the investigation; Sarah tries to track down Rosie's key; and Stan deals with his troubled son.

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

A return to the casino winds up sending Sarah and Holder on the run, while Stan and Richmond face life-altering decisions.

Sarah and Holder close in on the murderer. Meanwhile, the Richmond campaign preps for the election; and the Larsens seek to get their lives back in order.

Sarah and Holder's investigation comes to a close. Meanwhile, Richmond sets out on a bold new course; and a surprise source helps bring closure to the Larsens.