The third and nearly final episode commences with police snapping photos of Riz's lifeless body, revealing telltale signs of strangulation around her neck, indicating she was throttled before being cast into the lake's depths. Ember, her heart pounding, rushes to her mother's abode and queries how Sylvia knew Riz was found in the lake. Sylvia assumes Ember is referring to Amy, but Ember is startled to learn that her mother also knew Riz after she approached Sylvia in search of Amy. Ember explains her suspicion that Riz was probing Mack's involvement in Amy's disappearance, given that he was with her on the fateful night she vanished.
As their conversation unfolds, Ember recollects leaving Riz those fateful answerphone messages the night before, the ones that connect her, Mack, and Amy's case. Realizing the urgency, Ember hurries to Ember's house, hoping to retrieve the phone before the forensic team arrives, but alas, it's not there. DI Morgan convenes a briefing, dividing the team into two factions: one to unravel who murdered Riz, and the other to delve into the long-unresolved case of Amy Knightly. However, Ember's astute observation that Riz was investigating a sexual predator in their vicinity prompts DI Morgan to assign Ember and Hitch to their own specialized team.
The police interrogate Mr. Knightly relentlessly about the night Amy disappeared, and his alibi is riddled with inconsistencies for the time Riz was murdered. Despite his motive and lack of alibi, he insists he had no involvement in her death.
Back at her desk, Ember diligently traced the PI from the boat house using his car registration. The search revealed his name to be Gregory Blake. She promptly dialed his home number, but his wife answered with a frosty tone, clearly displeased with Ember's intrusion. Later, when Hitch proposed tracking down the PI using the same registration, Ember cunningly pretended ignorance, concealing the fact that she had already attempted to contact Gregory.
At the hospital, Ember engaged in a heartfelt conversation with Miranda, who had regained consciousness. Miranda revealed her intention to terminate her pregnancy, citing her preference for a carefree lifestyle rather than the responsibility of a child. Ember inquired if the baby's father had abused her, but Miranda shook her head, confessing that she didn't know who the father was as she "enjoyed having a good time."
Back at the police station, the team uncovered a significant call log from Amy's phone. A particular number stood out, one she had dialed repeatedly on the night she disappeared. As they dialed the number, Ember's phone rang from across the room, drawing everyone's attention.
During a police press conference for Riz's murder, Ember caught sight of Rosie through the window, the girl who had been arguing with Brad Ashby by the car. Ember excused herself from the conference and confronted Rosie, inquiring about the marks on her neck. Rosie confirmed that Liam was the culprit, but she refused to make a statement, fearing Liam's retribution.
Determined to uncover the truth, Ember confronted Liam directly. Her instincts proved accurate; Liam was indeed a pimp. While he might not be personally sleeping with the underage girls, Ember realized they were working for him. She demanded to see his phone, which was filled with half-naked images of young girls. The sight of Hannah, her own daughter, among those images left Ember deeply sickened.
Ember's fury erupted as she confronted Troy about spreading images of Hannah among his cronies. She pointedly reminded Hannah's mother that arresting Troy or Liam would mean arresting Hannah too, since she was the one who created the incriminating photos. Rather than confront Hannah, Ember stormed into the school and confronted Troy, demanding he delete the photos and provide a list of everyone who might possess them.
At home, Ember comforted Hannah, whose heart was shattered by the ordeal. Hannah tearfully apologized to her mother.
In a flashback, Amy and Caitlin arrived at the boat hut, where Mack introduced them to Joe, whom he claimed as one of his own. Caitlin and Joe were uneasy as Amy and Mack engaged in a passionate kiss. Joe's jesting about Mack having another girl on the side (whom we now know is Ember) enraged Amy, and she hurled her drink at Joe before storming out.
In the present, Ember visited a nursing home, where she spoke to Joan, Caitlin's mother. Joan was confused and unwell. When Ember mentioned her inability to locate Caitlin, Joan claimed she was dead, but her husband corrected her, saying they hadn't seen her for years. However, after he left, Ember spoke to Joan alone, and she whispered that Malachy killed Caitlin. Was she speaking the truth, or was she merely confused?
Back at the station, Ember was shocked to see Mack's name added to the suspects' board. She tried to convince DI Morgan that he was pursuing the wrong person, but her concern was evident. Suddenly, the phone rang. It was Hannah, her voice trembling with terror. She said a man was at her house demanding to see her. Ember kept her composure as the entire office listened, but her heart raced when the private investigator instructed her to meet him at the train station that night.
In the dimly lit car park, they met. Ember sternly told Gregory never to visit her home again, and he warned her not to contact his wife. The conversation turned to Riz, and Gregory informed Ember that the last he heard, she was tracking the GPS on her stolen laptop. He then played Ember a chilling recording from Riz's iCloud, where she confronted the laptop's thief. A strange wiring noise echoed in the background as someone strangled her to death.
Gregory informs her that Riz suspects Mack's involvement in Amy's disappearance. Not only does Mack have a criminal past, but the boathouse he once owned was mysteriously set ablaze two days after Amy's arrival. However, the true horror unfolded when Gregory revealed that he stumbled upon a human bone while photographing the boathouse. Ember was devastated, knowing that the bone was now sitting in her work locker, unreported as evidence. This reflected poorly on her, especially considering DI Morgan's already skeptical stance towards her.
In a fleeting memory, we witness Caitlin retreating into the boat hut after Amy and Mack's tumultuous confrontation. The sight of blood splatters on the floor and a blood-covered knife left her terrified, fearing that Mack had harmed Amy. After a heart-to-heart with her mother about the implications of keeping silent about the bones, Ember gathered her courage and ventured into the pub where the Ashbys, along with Hitch, were gathered. She confronted them, daring them to take a swab test if they were truly innocent of impregnating an underage girl. Yet, none dared to step forward, and Arj attempted to usher her out. But with Hitch's silent approval, Ember was left with no choice but to exit the pub, her heart heavy.
Unfortunately, as she exited, the police arrived, arresting her amidst the stares of those she had just challenged. With a heavy heart, Ember was forced to enter a police car, surrounded by the very people she had just confronted in the pub.
