'Under Salt Marsh' Ending Explained And Finale Recap: Who Killed Cefin And Nessa?

[Spoiler Alert] In Under Salt Marsh’s ending, Detective Sergeant Eric Bull and Ex-Detective Jackie Ellis finally solved the mystery centered around the murder of Jackie’s student, Cefin Hill, and her niece, Nessa Taman. As it turned out, both Cefin and Nessa were killed by one of Jackie’s distant relatives, Mac Jones, who was married to Nessa’s aunt, Nisha. But obviously, the important question here is: why did Mac murder two innocent kids in cold blood? And how did he keep it a secret for such a long time? Well, this bit’s a bit complicated, so allow me to dive deeper into the narrative so I can explain Mac’s methods and his motive in detail.

So, the show was set on a fictitious Welsh island, Morfa Halen, prone to massive storms that increase the sea level by 5 and 6 meters. The beginning of the show informed the audience that the island was going to be hit by another deadly storm, which would submerge the entire town. However, the people of Morfa had survived a gigantic storm some 5 years ago, using a sea wall as a shield against the rising water, but an environmentalist, Gareth Morgan, told them that they wouldn’t be so lucky this time, and they needed to relocate as quickly as possible. Okay, so how’s Mac Jones come into all this? Well, it was Mac’s construction company that had been building this stone wall, which was why he was so confident that his masterpiece would be able to protect the town. Mac and his employee, Dylan Rees (Jackie’s boyfriend), were building blocks for the wall inside an abandoned amusement park, Sunnyside. But here comes the interesting part. They weren’t just using cement and sand, but mixing toxic industrial waste in the mold. Why? The show didn’t discuss this in detail, but it could be surmised that Mac might have worked out a deal with some industry that paid him a hefty sum of money to get rid of their toxic waste material. And it shouldn’t come as a surprise that he had been helping these evil corporations and poisoning his people for more than 3 years. In a way, he was taking advantage of the town’s troubles to line his own pockets.

Once again, the show didn’t get into the details, but I believe it was Mac who arranged a deal between a factory and Cefin’s uncle, Ned Bevan, who allowed the industrial corporation to dump its waste on his father’s land. Solomon wasn’t aware of the fact that his son, Ned, had allowed an outsider to use his farm as a landfill and poison his family’s land. The show pointed out that Solomon’s farm wasn’t able to keep up with the expenses, which was why Ned made a deal with the devil just to earn a few bucks. However, things got worse when Jackie’s niece, Nessa, after being bullied by the Bevan kids, wandered deep into the quarry and fell into one of the ditches in the landfill. I guess it was true that Nessa had suffered severe injuries from which she might not have recovered, but that doesn’t give any person the right to kill her and bury her body.

Well, we have 3 people who were responsible for Nessa’s death and burying her dead body, because of which the police couldn’t locate her for 3 years. At first, we have Mac, who found Nessa lying in a ditch. She was still alive, but Mac suffocated her to death. Why? Because Mac believed that if he took Nessa to the hospital, then he would have to explain to everyone in town how she fell into a ditch full of toxic waste. It would put an end to the extra bucks he was earning by poisoning his neighborhood. So to bury his secrets, he killed Nessa and left her in the ditch. Remember when Osian Northam handed over a flyer to Jackie that read, “We are Poison”? That’s exactly what he meant. Later that night, Ned and his employee, August Antonov, found Nessa’s body, but once again, instead of informing the authorities, they buried her and covered it up so no one would ever be able to find out. Their reasoning was the same as Mac’s. They didn’t want anyone to find out about their secret landfill. And in order to keep his mouth shut, Ned paid August some extra money on the side, which he occasionally sent back home.

Now we don’t know the exact timeline around when Ned and Mac stopped dumping waste on his farm, if they ever did, but somehow, Ned’s sister and Cefin’s mother, Shell Hill, were aware of this landfill. Either she knew what her brother was up to, or maybe it was Cefin who told her mother about the dumping site, as Cefin used to wander around his grandfather’s farm after school. After Cefin’s death, Shell told Eric Bull and Jackie about this site, and this was how Eric finally located Nessa’s corpse. He had been trying to find the poor girl for 3 years, but due to a lack of evidence, he’d had to shut down the case. Meanwhile, Jackie was kicked off the force for misconduct after she punched Eric in the face for arresting her sister. She had told Eric as a friend that Nessa’s mother, Lydia, didn’t treat her well, which could be the reason the young girl ran away. But Jackie didn’t mean it. She was just sharing her opinion, and Eric took her for her word, and his actions not only ruined Jackie’s relationship with Lydia but also wrecked her friendship with Eric.

While Jackie was going through Nessa’s stuff, she found a drawing in which Nessa had drawn a man wearing a hazmat suit. I think Nessa saw one of the three men, Ned, August, or Mac, dumping waste in the landfill, and it could be possible that Cefin saw the same, which is why he drew a similar picture, which Jackie came across later in the show. What’s interesting here is that Cefin named this man in the hazmat suit as the Black Sow, a terrifying figure in Welsh mythology. Now, if you remember, at the beginning of the show, Cefin’s teacher, Jackie, told him, “If something frightens you during the day, at night it can come back and scare you. But if you face up to your fears during the day, they can’t get you at night.” So it’s likely that Cefin took his teacher’s advice and followed Mac, the man in the hazmat suit, from the landfill to Sunnyside, and when he finally found out what Mac was up to, he started screaming at him and threatened to tell Miss Ellis (Jackie) the truth. But before he could run away, Mac captured him and drowned him in the tub that they used to recycle toxic waste. It contained heavy doses of sodium hydroxide, which was why Cefin had nasty burn marks on his skin. Furthermore, Mac dropped his glasses in the toxic water, which was why he wasn’t wearing them when he showed up at the town meeting at the beginning of episode 1. Later that night, Mac dumped Cefin’s body in one of the drainage ditches by William Street, where Jackie found him. Okay, I’ll be honest here; I think I missed why the ditch in which Cefin was found had traces of seawater. I think it was because Mac might have used the truck that his employees used to transfer rubble from the sea wall construction site and Sunnyside. Also, only Mac and Dylan knew about their secret lab in Sunnyside, so it’s possible that Mac had hidden the body so Dylan couldn’t find it, and he removed it before Dylan arrived at work the next day. Throughout this time, Dylan was with Jackie, as the couple was having their private time, giving Mac the chance to get rid of the body without anyone’s knowledge.

Cefin’s best friend and Dylan’s brother, James Rees, was aware of the fact that Cefin was going to confront his fears, that is, face the Black Sow, but he didn’t go with him because he was afraid. Or maybe because Dylan might have asked him to stop fooling around and go home, but Cefin went to Sunnyside anyway. It’s also a possibility that James might have seen his brother wearing the hazmat suit, which made him believe that Dylan was the Black Sow that Cefin was referring to. And therefore, James hid the truth from Jackie and the detectives, because he didn’t want Dylan to get into trouble. However, when James went missing on the night of the storm, Dylan eventually told Jackie how they were recycling waste, but he promised her that he had nothing to do with Cefin’s death. This was when Jackie asked him who else had access to his hazmat suit, and as soon as Dylan told her about his master, Mac, Jackie connected the dots.

In Under Salt Marsh’s ending, Eric, too, figured out that there was something shady going on at Sunnyside which he went there to investigate further. At the secret lab, he came face-to-face with Mac, who locked Eric in a room and ran home. When he arrived at the house, Jackie, Dylan, and Nisha were already waiting for him and as soon as they started questioning him, Mac became aggressive and tried to escape. Dylan tried to stop him, but he stabbed him in the gut and ran away. At the same time, James arrived at Sunnyside and saved Eric’s life. He went straight to Mac’s house to arrest him only to find out that the man had run away again. However, when Eric found out what exactly happened, he didn’t go after Mac, but instead let Jackie follow him into salt marshes, as she knew the spot better than anyone. The reason being, she had spent months in those marshes looking for her niece, so even though Mac tried to hide himself, Jackie located him and asked him to surrender. Here, Mac tried his best to provoke Jackie, as she had a habit of losing her temper when things got personal, but this time, Jackie didn’t let Mac play with her mind. She grabbed him and tried to drown him in the water, and even though Eric could have stopped her, he refused to intervene. He knew this was Jackie’s fight, and he believed in her. He always saw Jackie as his partner, a detective who always stood by his side. And he didn’t lose faith in her even when she punched him hard in the face. Jackie had her reasons, and it cost her her job. Eric knew she had suffered enough, but he still believed that Jackie wasn’t a killer, which made him completely certain that Jackie wouldn’t kill Mac and would keep him alive so the law could give him the punishment he deserved. Well, thankfully, she didn’t let her anger hijack her conscience, and she let Eric arrest Mac and take him into custody. The show’s ending didn’t reveal what was going to happen to Mac from here onwards. After being hit with a massive storm, the town was still cut off from the rest of the world, so they had to wait for a bit to submit a final report to the higher-ups. In the meantime, Eric asked his partner, Detective Jess Deng, to contact the mainland for Mac’s mental health assessment. Eric and Deng believed that Mac might have also killed August Antonov, as he was going to talk to the police about Nessa, but they didn’t have the evidence to connect his murder to Mac. I do think it was Mac who burned down August’s trailer to either send him a warning or kill him, and when his attempt failed, he drowned August in the water to silence him. Ned, on the other hand, fearing for his own life, left town on a boat, and he might still be alive if he managed to survive the storm.

As Gareth Morgan had warned the residents, the storm submerged the entire town, and no one was really sure when things were going back to normal. But thankfully, there were no casualties, except for Osian’s sister, Carys Northam, who refused to leave her inn, The Ship, till the very end. The rest of the townsfolk took shelter in Solomon’s farm, which saved their lives. The people were a bit angry with Solomon because he lied to the police to protect his son, who gave access to an evil corporation to poison their land, but Solomon eventually sought forgiveness from them for hiding his son’s crimes and begged the residents to give him another chance, as he had their best interests at heart. Probably, once the seawater has receded, the people will try to rebuild Morfa Halen and go back to their normal lives. As far as Eric is concerned, he asked Deng not to hold back anything against him in her report. He told her that he was going to the same place. Eric had broken protocol by involving Jackie in the investigation, and it’s likely that he will be investigated for gross misconduct. However, the thing is, Eric wants to leave the job himself. He said as much to Jackie. He’s actually going away to France with his new boyfriend, Gareth. Maybe solving Nessa’s murder brings him the closure he has been looking for, and now he wants to just roam around a bit.

Meanwhile, Jackie, too, lets go of the past and starts her life again. For three years, Jackie has been obsessed with Nessa’s disappearance, but now that the case has been solved and the culprit has been put behind bars, Jackie can finally rest in peace. Earlier, she had been secretly meeting with Dylan and even got pregnant with his child, but she didn’t tell him about it because what Eric had done to her made Jackie lose trust in people. She started seeing everyone in the same light and wasn’t sure if she could trust Dylan and build a life together. However, the last few days made her realize that Dylan’s not a bad guy, and in the end, she finally accepted him. It’s likely that she will introduce him to her dad and her whole family and even tell them about their kid. Also, with Mac behind bars, it’s possible that Jackie and Lydia will be able to mend their relationship and move on in life. Well, it’s a happy ending for everyone, I guess, except for Nisha, whose husband was sent to prison, leaving her alone with her one-year-old kid, and of course Osian, whose sister was the only family and guardian he had. Well, these are my thoughts on the show, but if you have anything else to share, feel free to drop a comment below.