The third episode of "Under Salt Marsh" begins with DCI Eric Bull heading to the landfill. The police are conducting a thorough search of the area, testing for sodium hydroxide in the hopes of uncovering some form of evidence that will lead them to the killer.
Meanwhile, Eric Bull visits the school where Jackie is still reeling from the recent events. Given that a hair was found on Cefin's body, Eric explains that they need to interview James Rees - this time, officially. He invites Jackie to be present as well, knowing how valuable her presence can be in helping people open up.
After taking a DNA sample from James, Eric does his best to ease his nerves, but it's Jackie who ultimately helps loosen his lips. James eventually admits that he and Cefin were at Solomon's farm after school that day, with Cefin determined to face his fears. He was having nightmares about the Black Sow, a Welsh folklore legend surrounding a demonic supernatural creature known as "the Black pig of Halloween."
Eric Bull arrives at the farm, where Solomon immediately confronts the detective and plays hardball. He refuses to cooperate, which only serves to raise more alarm bells. Bull also notices that everyone at the farm is wearing gloves, which could potentially match the pathology report.
The main person they want to talk to is August Antonov, the Romanian farmhand briefly mentioned in the previous episode. Bull speaks to August, showing him a picture of Cefin, but the guy keeps saying "no English." Despite this, he can clearly understand what's being said, so Bull warns him that things could become difficult if he doesn't cooperate.
Jess speaks to his cousin, Nikov, who explains that August is "difficult." He complains about his job and seems to have come into some extra money, given that he's been sending a lot of money back home lately.
Jackie spoke with Eddie, Cathy, and a few other children who finally revealed their whereabouts on the day of Nessa's disappearance. Apparently, they had been playing on an old tractor near the quarry. The kids used to bully Nessa, cruelly forcing her to do things she didn't want to for kicks. They also threatened Nessa to keep quiet about everything or they'd hurt her.
On the way back, Jackie wondered if she might be wrong about the white suit. Maybe it was someone in a hazmat suit at the landfill rather than a beekeeper.
That night, Morgan called Bull, worried that someone had broken into his house. He caught them looking over some documents, and when Bull arrived, he chased the culprit as they fled. The only thing Bull managed to grab was a boot.
In the aftermath of this incident, Bull chalked up the entire attack to the townsfolk turning on Morgan, believing he might have something to do with Cefin's death. Bull knew it wasn't safe, so he brought Morgan over to the pub and demanded the landlady sort him out with a room. Jackie showed up at the pub not long after, and Bull guessed that she was pregnant. She kept her cards close to her chest and refused to divulge who the father was. However, Bull thought she should tell him (given nobody else in town knew) before it was too late.
Bull and Morgan then slept together before the former was called out to the landfill late that night. They'd found something. As Eric headed down, he realized they'd discovered Nessa's body. Jackie was crushed when she found out, and Bull explained that he'd even told Lydia too. Nessa had been buried there for three years, and it was a tough pill for everyone to swallow.
The next day, Morgan pays a visit to Bull, revealing that they haven't discovered sodium hydroxide at the landfill. This revelation suggests that Cefin's drowning was not at the quarry. Jess also deduces that August is being bribed to keep his mouth shut, explaining the extra money he's been spending.
Eric Bull realizes that they need to treat both cases as one and receives a message from the lab. The hair found on Cefin happens to belong to Dylan Rees, which is not going to help his relationship with Jackie, given how close she is to him.
Before they proceed with anything, Solomon shows up that night to confess.
