The episode of "Shetland" unfolds in London, the year being 2011. Annie Bett, portrayed by Sarah MacGillivray, steps into a cozy pub, where her path crosses with Euan Rossi, played by Ian Hart. Annie confides in Rossi, hinting at reservations, unsure if she possesses the mettle for the world he inhabits. Rossi clarifies that this is a matter of analysis, noting her invaluable assistance with the encryption challenge they previously assigned her. His team has been shadowing an individual with sinister intentions—bombing government edifices. Rossi assures her of an impending arrest. Nearby, a dramatic scene unfolds as a suspect is tackled to the ground and apprehended, all while Annie observes with a mix of awe and apprehension.
Flash forward to the present, Noah Bett, played by Jacob Ferguson, awakens from a slumber interrupted by a wet bed. His father, Ian Bett, portrayed by Robert Jack, rushes to his side, offering tender assistance. Meanwhile, in Rossi's quarters, Ruth Calder (Ashley Jensen) and Alison 'Tosh' McIntosh (Alison O’Donnell) engage in a conversation, pondering if Rossi's detective antics extend beyond mere games. Tosh expresses curiosity about whether Rossi would have disclosed the identities of Annie and Bergen's killers had he known. Ruth, uncertain, voices concerns that his actions might surpass casual sleuthing. She emphasizes the urgency of their departure for the airport, as Harding is en route for a confidential briefing.
Outside, DC Sandy Wilson (Steven Robertson) informs them of Rossi's disappearance since the previous day, his rental car abandoned nearby. Unbeknownst to them, Rossi is on a mission, scanning for a vehicle to commandeer. Spotting a man exiting a work van, he seizes the opportunity and makes his escape. Soon after, Rob Harding (Michael Higgs) arrives, joining Ruth and Tosh, and delves into Rossi's past, highlighting his creation of an intelligence team.
Back in 2013, Annie, under Rossi's employment, received intelligence suggesting the leakage of classified information. They devised a sting operation to ensnare the culprit, but fate had other plans. Annie was shot, and the intended target remained anonymous, suspected to be a foreign agent code-named 'Brutus.' A subsequent internal inquiry fingers Annie for the operation's failure, accusing her of acting alone without backup. This incident, labeled 'Brutus,' led to her dismissal from service. Rob warns that another life could be lost if Rossi locates the killer.
Returning to London in 2013, Annie visits Rossi, who conceals his intoxication. She reveals that tonight, at Gainsborough Flats, Brutus is expected to make a move within hours. Rossi retreats to the bathroom, indulging in drugs, insisting Annie should witness the capture. She reminds him of her lack of training for such tasks. Elsewhere, Ian prepares Noah for the impending events, briefing him on what lies ahead. Ruth and Tosh confide in Harry Lamont (Tibu Fortes) about Rossi, with Billy McCabe (Lewis Howden) mentioning the circulation of Rossi's details among them.
He revealed that a delivery van had been stolen, and the suspect's description bore an uncanny resemblance to Rossi. Cora McLean, played by Anne Kidd, informed Tosh that she had just received an email from someone at the National Ballistic Lab. The bullet extracted from Bergen matched a bullet from an unrelated incident in Manchester from the previous year, suggesting that both bullets were fired from the same firearm. The other shooting, a drive-by in Salford, fortunately resulted in no fatalities, yet the gunman remains unidentified. Sandy was entrusted with the task of identifying the SIO. Harry disclosed that Stefan and Mohan had been charged and released on bail. Ruth mentioned that Stefan was on a specific watchlist, hinting that he could be Brutus. Tosh shared with Ruth that Tara had been at the hospital with Annie when Bergen brought Astrid in. Apparently, Annie became distressed upon the arrival of the Jakobsons. They collectively decided to investigate the Jakobson family.
Stefan, portrayed by Johannes Lassen, learned that he couldn't leave due to the stipulations of his bail. Meanwhile, Euan Rossi approached the house as Karin, played by Nathalie Merchant, engaged in conversation with Astrid about the possibility of Stefan facing imprisonment. Suddenly, Rossi assaulted Stefan. Ruth told Tosh that Stefan had been stationed at the Swedish embassy in London during the time Annie Bett was shot. Upon their arrival, they discovered that Stefan had been attacked and Karin had been abducted. When Ruth inquired about his time at the embassy, Stefan revealed he was part of a trade and finance delegation, insisting the only noteworthy aspect was meeting Karin, who served as the defense attaché. Ruth stepped outside to inform Tosh that Karin was Brutus.
In a flashback, Rossi and Annie awaited Brutus, with Annie sharing stories about her homeland. In the present, Rossi extracted Karin from the truck and led her to the beach. Ruth called Sandy for reinforcement, only to learn that the stolen van had been spotted at St Ninian's Beach. Rossi compelled Karin to kneel, accusing her of targeting Annie once more. As Tosh and Ruth distracted him, Karin pushed Rossi and seized his gun. Elsewhere, Ian and Noah met Reverend Alan Calder, played by Steven Miller, who stated that everyone who loved Annie would gather together. They all proceeded into the church. Donnie Russell, portrayed by Angus Miller, informed the gathering that Tosh had wanted to attend but couldn't secure time off work.
At the station, Ruth and Tosh recounted that Karin claimed ignorance regarding Rossi's motives for kidnapping her. Karin had returned to Sweden after Annie was shot, yet there was no evidence linking her to Annie or Euan. Rossi underwent interrogation but remained tight-lipped about his reasons for abducting Karin. Ruth questioned whether Karin was Brutus and inquired about Rossi's reasons for hiring Annie. When pressed about the operation, Rossi revealed that Annie had uncovered the truth about his ordinary nature. In a flashback, Rossi exited the car to indulge in more drugs, painting a vivid picture of his descent into chaos.
Annie stepped out to ascertain his wellbeing, prompting Brutus to make his move. Rossi confessed that he had taken cover during that critical juncture, while Brutus aimed at Annie and made his escape, framing her for the operation. He revealed that Annie's voicemail was a prearranged signal for danger, one he had instructed her to use if she ever found herself in peril. Rossi speculated that Annie's predicament was intertwined with her past and felt compelled to act on her behalf, seeking justice for her.
Meanwhile, Michael Stack (played by Andrew John Tait) and Noreen Stack (portrayed by Lesley Hart) discussed with Alan about accommodating Lisa Friel (Tara Lee). Alan informed them that Lisa would be residing in the campervan until Angus regained his stability, cautioning that she might eventually betray his trust. In a private moment, Ian shared with Donnie that Noah had resumed wetting the bed, leaving him uncertain of the next steps.
Karin griped about her treatment, vehemently denying her involvement in Annie Bett's shooting and all other accusations. Ruth inquired about her whereabouts on the night Annie and Anton were slain, to which Karin claimed she had stayed at home throughout. Upon hearing Annie's perspective, Ruth swiftly relayed this to Harry and tasked him with proving Karin's alibi.
Lisa engaged Alan in a conversation about the absence of statues, questioning whether God makes people evil. Alan believed it was a choice people made themselves. Lisa countered that sometimes things simply unfold without apparent reason and decided to stay when Alan left to check on Angus.
Sandy discovered that Karin had made numerous calls to Stefan on the night of the murders and remained online until about 2 a.m., as evidenced by her IP address. This discovery caused Tosh to entertain doubts about Karin's guilt. Ruth informed Karin that they would scrutinize her time spent in London, promising to uncover any secrets she might be keeping. In a confidential moment, Tosh remarked to Ruth that Donnie felt she had been somewhat harsh on some of their friends. Ruth conceded that it was challenging being in a relationship with someone in law enforcement.
Later, Ruth confronted Rossi, informing him that Karin couldn't have been at the Croft on that fatal night.
She steadfastly insists that if she were Brutus, they would inevitably apprehend Karin. Ruth, sensing his lingering distress, urges him to release the shackles of his shame. Rossi elaborates on the reasons why the past continues to haunt him, unable to escape its grasp. At home, Tosh engages in a heartfelt conversation with Donnie, who expresses his unwavering pride in her achievements.
In a vivid flashback, Rossi confides in Annie, suggesting that he has the courage to return and reveal the truth. Annie gently reminds him that it's time to return to their roots. Noah is tormented by a nightmare, lashing out at Ian in frustration. Ruth steps in to comfort Noah, addressing his terror-filled dream. Noah recounts a harrowing tale of being trapped in the Croft with his mother, chased relentlessly by a menacing lizard. Despite her desperate attempts to shield him, the lizard invariably catches and consumes him, leaving Noah terrified.
Sandy contacts Tosh with crucial information, revealing that he has spoken to the SIO regarding the Manchester drive-by shooting. Cora's hunch was accurate; the shooter remains at large, but their investigation has pinpointed a suspect named Kyle Frost. He forwards a photograph of the individual, prompting Tosh to recognize him instantly. Urgently, she requests a unit to converge on the Seaman's Mission, where she last encountered Kyle.
Ian and Ruth discuss the possibility of seeking professional help for Noah, and Ian confesses his bewilderment. Ruth's brief update on the case hints at progress, but she also wishes to share insights about Annie's background. Meanwhile, Tosh and Sandy embark on a mission to locate Kyle Frost, alias Killian Coyle. When Pan Ran saw the two, he tried to evade arrest. However, Tosh was quick and quickly locked his whereabouts. Facing the approaching police, Kyle tried to escape again, but stopped halfway and questioned the reason. Soon, Kyle was detained according to law.
Ian confronts Ruth with the overwhelming information, expressing his struggle to comprehend it all. He mentions Noah's request to contact her, and Ruth promptly returns to the station where Kyle is being grilled about the Manchester shooting. Kyle reveals he relocated to Shetland nine months ago, seeking a fresh start. Tosh confronts him with the gun linked to the double homicide, but Kyle remains non-cooperative, claiming he was DJing at the mission until the early hours of Friday morning.
Sandy interrupts the interrogation, having uncovered incriminating evidence on Kyle's social media accounts. Photos depicting him in Manchester and on the Isles surface, including one with Lisa Friel. As the investigation deepens, Lisa remains secluded within the church, unaware of the turmoil unfolding around her.
