Sarah (Laila Rouass) was hired by ARC to help the anomaly team. Nick (Douglas Henshall) and Sarah are working on trying to identify all the anomalies throughout history. They are hoping to find a pattern that will aid them in predicting them. Connor (Andrew Lee Potts) is working on a device that will seal the anomalies once they are found. In the meantime, a reporter named Mick Harper (Ramon Tikaram) is nosing around ARC looking for a story. Everything is interrupted when an anomaly opens at the West London Hospital. The entire team heads over there to investigate. Mick follows the team to try to find evidence of dinosaurs.
The anomaly has released a group of Diictodons into the hospital. Although they are somewhat cute, they are highly destructive. Their propensity for chewing and burrowing causes them to eat through the electrical system of the hospital. One pregnant woman, Melanie (Nina Toussaint-White), described them as, a ratty chipmunk beaver kind of thing. The team tries to round them up but two of them end up left behind when the anomaly closes.
Meanwhile, Helen (Juliet Aubrey) has an army of cloned Cleaners (Tim Faraday) and plans on attacking ARC. To facilitate the invasion, she has also cloned Nick. When the team returns, they are imprisoned. Helen confronts the real Nick wanting to know what the artifact she stole from the future is for. Helen believes that what Nick and the ARC are doing will bring about a world dominated by future predators. She also believes that, to stop that from happening, she needs to destroy ARC and kill Nick.
Episode 3 of season 3 features Diictodons. A Diictodon was a small burrowing herbivore from the Permian period. They were closely related to mammals.
The Artifact was a piece of future technology. It is believed that it was created by an alternate future Anomaly Research Center. The device was a time map that showed every Anomaly past or future. The information contained in the Artifact could only be accessed by a high-tech computer that was also from the future.