Warning: Major spoilers ahead

Bull and Deng begin questioning Solomon. He informs them that, since Cefin’s death, he’s begun to consider things differently. Three years ago, he was told about the quarry being used as a landfill. When he went to the site to examine it, he found Nessa’s body among the piles of chemical waste, badly burned. He picked up the body to look for signs of life, before wrapping her in a tarp and burying her in the landfill.

Solomon says he did it because the farm had been his livelihood for seven generations, and he was scared of his family losing everything if it was discovered. But Bull isn’t convinced, asking why he felt the need to wrap the young girl in a tarp and leave her in the toxic waste. He asks him who it was that told him about the landfill site to make him go and look in the first place, concluding that someone else must have been involved. Solomon insists it was just him who found her.

At Dylan’s house, Jackie continues to have her nightmare about looking for Nessa amid the marsh reeds. When she wakes up, she shares that her sister, Lydia, is due to arrive today. As she leaves, she spots Deng arriving. She ducks behind a van as Deng makes her way to Dylan’s front door and leaves unseen.

When Jackie arrives at her dad’s house, he informs her that he, Lydia, her spouse and his family will be gathering to grieve, having now been informed of Nessa’s discovery. She realises she’s not been invited, as Lydia is still upset with her after being accused of involvement in Nessa’s disappearance in the initial investigation. Her dad says he wants to stay out of the siblings' issues.

At the investigation HQ, Deng hands Bull the DNA swab Dylan gave her, noting he handed it over willingly, though was confused as to why he was giving it. Shell arrives with a replica pair of wellies that Cefin was wearing when he went missing, thinking it would help the investigation, but they’re interrupted by the arrival of the Bevan brothers, who demand to see Solomon.

Jackie spots the commotion and gets involved, asking if they were aware Nessa had spent three years buried on their land. As Bull tries to calm her down, Shell speaks to her brothers in Welsh, saying they’re refusing to let anyone see Solomon. They jump to the conclusion that he’s been arrested. Jackie overhears this and asks Bull to confirm it, which he won’t. He removes Jackie from the scene by asking her to step into his car.

Inside, Deng looks up Bull and Jackie’s work history – finding that Jackie had been forced out of the police for gross misconduct. Spotting a restricted file, she unseals it to find a series of videos that include Bull arresting Jackie’s sister, Lydia, on suspicion of Nessa’s murder.

Jackie is seen bursting in and obstructing the arrest, causing an argument between her and Bull, who reminds her she’s under direct orders to not be there. Bull reveals he’s acting on concerns that Jackie shared about Lydia’s treatment of Nessa. Enraged, as she told him that in confidence and off the record, Jackie punches him. Lydia is led away while demanding to hear what Jackie told him.

Jackie and Bull drive out of Morfa Halen. Leaving Jackie in the car, he meets with Irene from forensics and supplies her with Dylan’s DNA sample and to discuss the results of Nessa’s autopsy. Nessa’s body, preserved from the waste on the land, was essentially mummified, but was severely burned – likely by the toxicity in the waste. However, it wasn’t what killed her. She was suffocated and murdered in a manner similar to Cefin. Irene notes the bruising on the back of the neck, with the handspan of both being about the same.

Jackie doesn’t stay in the car for long, and when she sees Irene, she snatches the case folder. Bull grabs it back off her, but once they’re back in the car relents, handing the file over, but warning her about its contents. She immediately regrets it, and Bull pulls the car over so she can get some fresh air.

Jackie shares her guilt at not finding Nessa sooner, and how they have to find the killer once and for all.

Later that day, Jackie heads to the sea wall and sees Dylan working, while Bull heads to the bar to find the Bevan siblings and ask questions. He asks them about the farm’s financial state, believing they had deliberately leased out some of their father’s land to serve as an illegal landfill without Solomon’s knowledge.

Bryn refuses to talk, saying they’ll need to be arrested before they answer any more questions, but Bull tells them Solomon has confessed to Nessa’s burial, and that he knows two of their sons had broken into Gareth’s house in a bid to get information on the landfill. Their denial falls flat quickly when Bull reveals the trainer he grabbed off him in their scuffle was labelled with his name. Kath refuses to believe it, but when she asks her brother to deny it, he instead walks off with his sons.

Kath and Ned remain, and Bull says he won’t arrest the boys if they talk about what happened with the land. Ned admits contracting out the field, but says he stopped it around three years ago. Bull questions why, suggesting he stopped it after Nessa’s death and therefore knew about it, but Ned denies it, saying he wasn’t involved in the day-to-day functioning of the land. He also refuses to hand over a name.

Back at the police base, Bull starts to break Solomon by showing him pictures of Nessa’s injuries – including bruising to the back of her neck from where she was held down. He insists he just found and buried the body; he didn’t kill her.

Bull notes she died in the same way Cefin did, and requests to see his hands, because the handspan suggests the same person killed both the kids. Solomon is horrified as Bull starts laying into him for protecting someone who killed a little girl – and asks if it was one of his children or grandchildren, as he could see no other reason for it. He eventually explodes into a rage, demanding Solomon leave for wasting his time, telling him he’s free to go.

Deng, who was present throughout the entire thing, finally tires of Bull’s behaviour and storms out of the room.

That evening, Jackie turns up at Nisha and Mac’s door, despite not being invited, to join in the memorial prayer for Nessa. While Lydia and her husband Dev decide to ignore her to focus on the ceremony, nerves get the better of Jackie, who drops a tray when Lydia hands it to her. She immediately apologises but the moment is ruined, and Lydia goes to the kitchen to clean herself up.

Jackie follows her, apologising again and realising she shouldn’t have come. Lydia says she can stay if she wants. Jackie said she came to see her because she misses her and wants them to be a family again. When Nisha tries to restart the ceremony, Jackie is asked to join in but she declines, and instead makes her case to Lydia, saying she loved Nessa, making her break down in tears as she pushes things too far. Jackie’s eventually kicked out by Mac, who tells her to pull herself together and stop dragging everyone down with her.

The hotel bar is completely dead, with people opting to avoid the Bevans after news of the body spreads around the village. Bull gets a call from Irene, who confirms the hair on Cefin’s body was that of Dylan, but the call is cut off due to bad reception.

Gareth, still sporting a black eye after the Bevan kids attacked him, crosses paths with Bull as he plans to return home. Bull stops him, pressing him against the wall and kissing him. Gareth turns him down, pushing him away, with Bull trying to make it violent before Gareth calms him down. Walking off in a strop, Gareth comments that he was different two years ago, prompting Bull to tell him it was actually four – because he doesn’t do “this kind of thing that often”.

He continues to be aggressive to Gareth, demanding he stop walking away from him, but Gareth tells him he’s heading back to his house to pack his things and leave: the storm is approaching. A weather warning is set to be issued, and an evacuation order will be put out. Panicked, Bull’s first thoughts are regarding the ongoing case. Gareth reminds him storms don’t care about his investigation.

The next morning, Jackie finds her dad packing to get out of Morfa Halen alongside Lydia and Dev. He encourages Lydia to persuade Jackie to leave too, but when Jackie tries to apologise again, Dev scolds her for continuing to drag up the past to them. Jackie insists she’s doing it for Ness, but Lydia tells her she didn’t want her to do anything, just be there to support her. Jackie thinks she’s talking about her arrest, blaming Bull for the decision – but Lydia reveals she knows she’d told him she’d lost her temper with Nessa, and that was what caused him to become suspicious. She was always innocent and didn’t need Jackie to prove that. Before leaving, she tells Jackie to do what she wants – but to stop lying to herself that it’s for the family.

Bull goes to talk to Dylan, who is looking after James and is less-than-pleased to see him. James is still suffering from nightmares and is curled up in a ball on the sofa. Taking the conversation away from James, Bull shares the hair found on Cefin was a DNA match for Dylan, and asks him again for his whereabouts, especially as he was seen leaving the town meeting early.

When he says Jackie is his alibi, Bull is confused, asking why she wouldn’t have brought that up, prompting Dylan to laugh and call him “dumb”, revealing he’s been secretly seeing Jackie for about a year. When asked why it’s a secret, Dylan tells him to ask her.

With most lines of questioning heading nowhere and the town now beginning to evacuate, Bull is more frustrated than ever. Deng suggests they interview the farmhand August, as he’s been wiring large cash sums to Romania for over a year. Bull encourages her to follow the lead, but pushes back when she asks about Dylan, not wanting to spill Jackie’s secret yet.

At the Bevans’ Farm, Solomon is visited by Jackie, who shows him the picture Nessa drew shortly before she died - the man in the astronaut/beekeeper/hazmat suit - and says she needs to know who it is. She understands the struggle to accept someone you love being capable of murder. When he says he would never accept something like that, Jackie says she can see in his eyes that there’s doubt, which angers him.

Solomon snaps, saying he would never turn his back on his family like that, and tells her to get out. As she does so, Deng spots her.

When Deng visits August, she asks about the money she sends home, and once again, he pretends he doesn’t know English. Deng doesn’t buy it, saying her mother, who’s Chinese, did the same trick. He softens, asking questions about her, and she pushes about the money, deducing that he must be getting either hush money or blackmail payments.

August calls her a good person. He asks if he tells her the truth, if she’ll act on it. When she says yes, he shares that there's more waste coming into Morfa – arriving at low tide via truck every Thursday. He can’t say who but tells her if she waits by the causeway this evening, she’ll be able to see for herself.

She informs Bull who meets her at the causeway. She criticises him for keeping Jackie involved in the investigation, and he tells her she can be useful. While Deng agrees not to report him, she shares that she saw her at Solomon’s Farm earlier that day.

Bull storms off to confront Jackie, pounding on her door. She ignores him as she continues to look through her files on Nessa, smashing a glass against a wall in the process. When she finally relents, she cuts her foot, and he’s furious that she’s kept so many case files despite her no longer working on the force.

As he helps her get the glass out of her foot, things begin to get hectic on the causeway as the water hasn’t lowered - those who are trying to evacuate realise they’ve been completely cut off. The storm surge has arrived.

With time against them, Deng tries to return to August’s house, while Bull and Jackie head together to the hotel to see if he’s there. On route, Bull shares that he knows Dylan is the father of her unborn baby. However, he lies about why Deng was at the house, deciding to protect her.

She apologises for being so angry with him about what happened to Lydia, knowing she was to blame, but wants him to admit that he was wrong too. He doesn’t say anything. Instead, he shares that when he was a kid, he had a friend that died.

At the pub, the hatches are being battened down. The townspeople are in high spirits despite the coming storm, but August is nowhere to be seen. Suddenly, Oisian breaks up the party, yelling for help outside – there’s a body floating face down in the sea. Bull jumps in to pull them out… it’s August.