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.

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.

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.

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.

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

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

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.