Old wounds are painfully reopened for the shocked residents of Ravenswick, as Detective Inspector Jimmy Perez and his team look to a past crime to solve the present day murder of a young teenage girl.

Detective Inspector Jimmy Perez believes he and his team are finally closing in on the killer as they discover what 17-year-old Catherine Ross was hiding from everyone in the hours before her death.

When an old acquaintance of Detective Inspector Jimmy Perez dies in a suspicious car accident on the island, he wonders whether his journalist friend had uncovered a story that cost him his life.

After a second body is found brutally murdered on Shetland, Detective Inspector Jimmy Perez wonders if the two killings are connected to corporate greed and corruption on the island or to just one woman - Evie Watt.

Perez returns to his childhood home after the murder of a scientist on the beautiful island of Fair Isle. Tensions run high as a storm on the mainland forces Perez to work in isolation - and compels all of the suspects to remain together under one roof.

Time is running out for Detective Inspector Perez as prime suspect Peter Latimer lies critically ill in hospital. Was the fire a drunken accident, or was Peter Latimer the second victim of a murderer still free on Fair Isle?

When a young man disappears on the Aberdeen to Shetland ferry crossing and a small boy ends up in intensive care, DI Jimmy Perez and his team investigate, becoming convinced the two events are connected.

DI Jimmy Perez is convinced that Michael Maguire is somehow implicated in the death of Robbie Morton. But with the investigation seemingly under threat before it's even started, he faces an uphill battle to uncover the truth behind Maguire's silence.

The murder investigation takes Perez and Tosh to Glasgow as they try to uncover the reasons behind Maguire's brutal death and his connection to Robbie Morton. But old ghosts return to haunt Perez as his enemies try to prevent him from getting to the truth.

Perez and his team are determined to track down the person who helped Michael Thompson's killer on Shetland. But the closer the team get to the truth in both Shetland and Glasgow, the more dangerous it becomes for all of them.

Perez struggles to deal with what has happened to Tosh as he continues to investigate the murders of Robbie Morton and Michael Thompson, but a shocking discovery finally leads him to the identity of who Thompson was going to testify against.

As the investigation reaches its final stages, Detective Inspector Perez and his team discover the person responsible for the deaths of Robbie Morton and Michael Thompson is closer to home than any of them thought.

When Thomas Malone has his murder conviction overturned after 23 years behind bars, DI Perez has to reopen the investigation into the 1994 death of local teenager Lizzie Kilmuir.

Perez is on the trail of an attacker, Tosh investigates an oil company in the hunt for Sally's killer, and DNA testing in the Kilmuir case yields a surprising result.

Jimmy questions Donna about the shocking DNA results, Alison arrives in Norway in search of Andreas Hagan, and an unexpected twist leads Perez and Tosh into the murky world of the Norwegian far right.

Ignoring Secret Service warnings, Perez and Tosh track down Mathias Soderland. Back on Shetland, a beach memorial service is held for Sally McColl.

Perez must re-assess the investigation in the aftermath of the attack. The MIT arrives on Shetland and sets its sights on Malone. Meanwhile, Tosh begins to have doubts about Lars.

Season Finale - Troubled by historical DNA evidence results, Jimmy has to face the fact that Duncan may have been involved in Lizzie Kilmuir's murder, and potentially Sally McColl's as well. A shocked Duncan is brought to the station for questioning, hurt that Perez would even think him capable of murder. However, the detective knows Duncan's lying - perhaps not about the murder, but about something else significant. So when Duncan finally admits he had an affair with Donna, it's not long before a bombshell is dropped.