Connor and Abby are sent to investigate unusual anomaly signals in a coastal village and uncover the existence of a supposedly mythical Labyrinthodont that has turned its attentions to the local fishermen after attacking cows. Meanwhile, back at the ARC, Lester and Jess learn that Emily has been kidnapped by Ethan, prompting Matt to make a dash to a cemetery - where he faces a difficult choice.
A boy who created a superstition about the Witchfield Worm goes to investigate and try and find the creature when livestock starts disappearing. he had set up a tent and was taping at night when the creature escaped and ate the boy taping on the cliff above the cave where the creature came out of. Connor, Abby and Matt are sent to investigate an odd anomaly signal, which keeps appearing and disappearing from the ARC sensors. They travel to a small coastal village, where myths about a worm attacking local farm animals are rife. After investigations involving unhelpful locals and Matt discovers body parts of the boy in a river where a fisherman is fishing and was attacked by the creature, but was saved by Matt, they then realize they are tracking a dangerous Labyrinthodont, which started by attacking cows, but has now moved on the people.
Meanwhile, Matt is disturbed by Emily’s disappearance, tells everyone except for Becker and Phillip about, after learning of this Lester calls him dumb for not telling them about Emily and also for not bringing her into protective custody,.as Emily thought she will be treated like a freak but Lester tells Matt that she would be protected. After encountering the creature, Jess tells him that she has some clue on Emily's disappearance on a camera outside his flat: Ethan has kidnapped her.
As Abby searches the creature, Connor is ordered by Philip to track down the unusual anomaly signal. When he finds it in a cave near the coast, he also discovers this is where local farmers have been hiding the remnants of a fuel smuggling operation. The dangerous chemicals have been wreaking havoc on the anomaly signal, preventing it from opening fully, and making its signal weak and random. At the same time, Abby finds the creature where it tried to eat a boy but failed and chases Abby instead who locks herself in a truck where the amphibian climbs on top and tries to attack Abby while she drives the creature to the anomaly but the creature smash the car window next to Abby and she was knocked unconscious. Before the creature devours Abby, it hears the screams of a smaller amphibian that is dying by the acid and was disturbed by Connor and retreated to the cave.
Philip is over the moon with Connor’s discovery; forget the creatures, this is the real information they need. Before Connor could open the anomaly, one of the farmers knocked him out and let his mother to see the worm which she told was a bluff. Connor then finds out that they had been pouring diesel into the cave from their farm and that the farmer build and opened the gate and practically murdered the boy last night. Before the farmer could kill Connor with his shotgun, he and his mother were eaten by the amphibian. When Jess tells Connor that Abby's black box was in front of him, he thought that she was eaten by the creature and he finds out that the diesel, when diluted with the acid, opens the anomaly during his fight with the amphibian until the creature was about to kill Connor whereby Abby who surprised Connor who found out that the creature only swallowed her black box shoots the creature with the dead farmer's shotgun. Connor then throws diesel which open the anomaly and both creatures went through. After Connor tells Abby not to let him think that she was dead again, he kiss her and both drive back to the ARC.
Meanwhile, Ethan has taken revenge on Emily by kidnapping her. He is determined she will suffer the same fate as his beloved Charlotte as he says that Charlotte needs a proper funeral service, and so plans to bury her alive in a coffin in a family mausoleum in the Cameron section which is Emily's dead friend, Charlotte Cameron. Matt manages to get her just in time to save her life, but despite his best efforts, Ethan still escapes. Matt’s flat is no longer safe; he can’t be sure Emily will be protected there. There’s only one place left to go: the ARC. After that, Gideon tells Matt that one person does not need to fight an army or need money and power but needs knowledge only after referring to how damage Helen reaped upon humanity. Connor also joins and works Prospero Industries, which he is not suppose to mention to anyone, in his free time.
- Ciarán McMenamin as Matt Anderson
- Andrew-Lee Potts as Connor Temple
- Hannah Spearritt as Abby Maitland
- Alexander Siddig as Philip Burton
- Ben Miller as James Lester
- Ruth Kearney as Jess Parker
- Ruth Bradley as Emily Merchant
- Jonathan Byrne as Ethan Dobrowski
- Anne Kent as Moria Lennon
- Brian Gleeson as Ray Lennon
- Johnny Ward as Ted
- Mal Whyte as Barman
- Duncan Lacroix as Neil
- Bradley Burke as Boy
- Matt Anderson
- Connor Temple
- Abby Maitland
- James Lester
- Jess Parker
- Philip Burton
- Ethan Dobrowski
- Emily Merchant
- Moria Lennon (only appearance)
- Ray Lennon (only appearance)
- Ted (only appearance)
- Barman (only appearance)
- Neil (only appearance)
- Boy (only appearance)
- Labyrinthodont (only appearance)
- Anomaly Research Centre
- Witchfield Cove (only appearance)
- Lennon Farm (only appearance)
- Seaside Cave (only appearance)
- Haven Holidays caravan park (only appearance)
- Tower Hill Cemetery (only appearance)
- Matt Anderson's flat
- Ethan Dobrowski's flat
Objects and technology
- When Matt releases Emily from the coffin in the Cameron family mausoleum, Emily can immediately be seen hugging Matt for rescuing her with free hands. However, in a scene directly afterwards, we see Matt untying Emily's hands which were free moments before.
- The Labyrinthodont has been extremely exaggerated in size and has a scaly appearance instead of smooth soft (amphibian) skin. It is also able to stay out of water for long period, unlike amphibians.
- In reference to Episode 4.4, Becker does not appear because he is on medical leave following his injury.