Meanwhile, at the ARC, the anomaly detector bursts into life. As Connor tries to determine the location of the anomaly, the machine crashes without warning. A diagnostic report reveals that the detector is infected with a form of spyware, allowing the hacker to divert the details of the anomaly to wherever he/she is.
Elsewhere Leek has intercepted the details and quickly traces the location from within his car. He then makes a call to the "cleaner" and his band of mercenaries. Leek slips quietly away and goes to the anomaly, where he finds the heavily armed group of mercenaries waiting for him. They enter the anomaly, while Leek waits in the present day for them to return. At the same time, Stephen returns to his flat to find Helen Cutter in the shower. She comes out and talks to Stephen, warning him that there is a traitor among them. When Stephen leaves her for a moment, she calls Leek and demands a report. Leek replies that his men haven't returned and Cutter has arrived at the anomaly site. He leaves the area, after being warned what will happen if Nick finds out what's going on.
In the Silurian desert the mercenaries see Taylor stranded on a rocky outcrop, but refuse to help her. Suddenly the sand starts moving beneath them. Taylor yells at them to 'get off the sand' but it's too late. She covers her ears as she listens to the screams and gunfire echoing in the distance. Finally the desert swallows them up, leaving nothing but their scattered weapons and a deathly silence.
Meanwhile Connor manages to locate the anomaly, out of which Sprat comes running. Nick guesses that Sprat's owner must be on the side of the anomaly. After sending a machine equipped with a camera through the anomaly to determine what is on the other side, the footage shows Taylor sat on some rocks in the middle of a sandy desert. The team deduce that she is trapped in the Silurian and Stephen and Cutter enter the strange Silurian world in the hope of rescuing her. The high concentration of carbon dioxide and low oxygen makes it hard to breathe and the going for the pair is tough. After walking a fair distance, Cutter and Stephen find weapons and a night vision camera littered on the sand. Determining that whoever was here before them wouldn't have left all their belongings behind, Cutter checks the film. The film shows the solders being attacked by some sort of creature that emerged from beneath the sand. Cutter is determined not to leave anything behind and the two men pick up equipment and weapons and pack it away safely. As they gather up equipment, Steven comments on the possibility of a traitor within the A.R.C: when Nick makes comments that he knew this, Stephen angrily argues that once more Cutter is keeping things from them, and that they're supposed to be working as a team. Nick simply replies that Stephen 'sounds like Helen'.
The sand starts to move beneath them and they realise they have to move off the treacherous dunes as quickly as possible. Taylor yells at them to 'get off the sand' and they join her on her small rocky outcrop. She explains that the creatures are attracted by their movements on the sand: as they watch, dozens of strange creatures snap and claw from below the sand.
On the other side of the anomaly, Connor tells Abby he intends to break up with Caroline by text. Abby tells him that this would be an unkind move, but Connor decides to break up his relationship through this method anyhow. Suddenly a strange insect, a long multiple legged creature comparable to a millipede, comes through the anomaly. Connor and Abby chase it as it gets away, but as they run off, the anomaly begins to close. They run into a cafe and catch it in a ballpit, (Abby succeeds in fishing out the millipede, but Connor seems more interested in enjoying himself, stating that he used to love playing in ball pits when he was younger). Just after they have returned the creature back through the anomaly, it closes. Horrified, the pair return to the A.R.C and inform Lester. Connor and Abby are put in charge of the anomaly project- much to Lester's chagrin- and they are told to watch for future anomalies opening in the hope Cutter and Stephen return from it. When Jenny asks what she is meant to tell Taylor's step-father, Lester answers simply "Tell him we did our best". At this moment, Caroline receives Connor's text and in a fury, takes her frustrations out on Rex, throwing various items at him before finally knocking him out and taking him with her.
Cutter, Stephen and Taylor move across the rocky terrain as fast as they can, but the anomaly closes before they reach it - they are stranded. They encounter the mystery man Nick knows as 'The Cleaner'(the mercenary leader), who tries to take their equipment and water from them, but is then killed while shooting the sand- the noise attracts one of the burrowing creatures, which emrges and seizes him. When Stephen and Cutter try and force the man to tell them who he's working for, the Cleaner snarls coldly "I'm a professional. I don't talk, ever!". The creature then drags him under the sand to his death.
With no more rocks to walk on, the trio are forced to walk slowly and carefully across the dunes to avoid attracting attention. However, Taylor slips over and the vibration attracts one of the creatures. The creature drags down Steven, and when Taylor jumps up and down on the sand to attract its attention, it emerges. It is a gigantic scorpion, with immense pincers and a long, whipping tail that holds Stephen in its claws. It advances on them, but another one leaps out and the two scorpions fight. During the confusion, Stephen escapes, and a new anomaly opens. The three use a giant shell (that was knocked off one of the scorpions during the fight)as a sledge which they slide down a sand bank in and end up sliding through the anomaly.
They arrive in a forest and find a primitive tent and weapons, and Cutter concludes the anomaly may have taken them to the Paleolithic. Suddenly, a prehistoric Caveman appears, holding a spear. He is quickly knocked out by Cutter, who discovers that he is simply in a prehistoric theme park and that the caveman was an actor. They are met by the rest of the team. Lester welcomes Cutter back, saying he'd rather Cutter running the anomaly project than Connor, but Cutter deals with him suspiciously, remembering the acusations of treachery among the team. They return Taylor to her family, and Nick offers her a job at the A.R.C jokingly when she is older.
Back at the ARC, Cutter puts the night vision camera on his desk, and goes for a coffee. When he returns, it is gone.
Creatures seen: giant scorpions(at least 2 are seen in the past) giant milipede(1 entered the present returned home) coelurosauravus(hit with tennis racket by Caroline)