A year after becoming marooned in the past, Connor and Abby return from the Cretaceous to a changed and upgraded ARC, but Connor accidentally brings a Spinosaurus back to the present with them.

While Connor and Abby try to earn their old positions on the team back, Connor reunites with his old friend Duncan, who leads Connor to a series of homeless killings at a dock area that the team discover are the work of an elusive and deadly Kaprosuchus.

When an Anomaly opens at a theatre, a group of mysterious Anomaly travellers come through, followed by fast and deadly Tree Creepers. Meanwhile, Connor helps Philip design a new security system for the ARC, but it goes horribly awry and sends the ARC into lockdown, and time is running out for Connor to free Rex and Philip before the system suffocates them.

Matt, Connor and Becker investigate an Anomaly at a secondary school and struggle to save the remaining students from deadly, venomous Therocephalians. Meanwhile, Philip decides to have the ARC's captive creatures including Rex euthanized, prompting Abby to try and smuggle them to safety before it's too late.

The team investigate an Anomaly incursion at a rural manor house, and reunite with Jenny and discover that the manor is the location for her wedding in the morning; forcing the team to contain a pack of Hyaenodon while ensuring Jenny's soon-to-be-husband doesn't find out. Meanwhile, Jess and Becker are caught in Ethan's deadly trap.

The team head to an old prison, where they discover an Anomaly that won't lock and is producing satellite Anomalies throughout the prison, which in turn makes it even harder for the team to track a Terror Bird loose in the prison. At the same time, Danny returns from the past with a warning for the team, Ethan's true identity is discovered, Emily is torn between Matt and the chance to return to her home, Matt reveals his secret, and Connor makes a terrible discovery.