Eight years after his wife Helen mysteriously disappeared, Nick Cutter and a team of several others investigate reports of a large animal in the Forest of Dean, and discover that mysterious Anomalies in time and space are appearing and allowing prehistoric creatures to cross into the present day.

When a pest controller is attacked in the London Underground and landed in hospital poisoned with venom, Cutter, Claudia and the team investigate and discover the Underground is infested with giant, Carboniferous spiders. Cutter and the team soon learn that the true culprit is not the spiders, but a giant centipede, and they are sent in a race against time to get the centipede's venom after it poisons Stephen.

Meanwhile, Connor gets thrown off the team after telling two of his friends about the Anomalies, and attempts to earn the team's faith back in the fight against the giant centipede. At the same time, Cutter's suspicions that Helen is alive on the other sides of the Anomalies increases.

The team are called in to investigate when a lifeguard is eaten by a Mosasaur at a swimming pool. Cutter discovers that they are dealing with a mobile Anomaly when the Mosasaur and the lifeguard's vomited remains appear at a reservoir and a cellar floods and is invaded by a Hesperornis. The rest of the team also learn that Helen is alive and on the other side of the Anomaly, and so Cutter is forced to go through and confront the woman his wife has become.

Helen Cutter directs the team to an Anomaly at a football stadium and escapes through, leaving behind a flock of Dodos. The team soon discover that the Dodos are host to a deadly parasite, and struggle to stop a pandemic when Tom is infected and - convinced that the government are incubating a mind-controlling biological weapon inside him - goes on the run from the team.

The team investigate the brutal death of a golfer at a golf course, and discover an aerial Anomaly and a Pteranodon in the skies above. Claudia is convinced that the Pteranodon is responsible for the golfer's death and wants deadly force used against it, but Cutter and Stephen are convinced otherwise. Cutter's suspicions are confirmed correct when Claudia is trapped in the golf course's clubhouse by a deadly, flesh-eating swarm of Anurognathus.

Meanwhile, Connor accidentally frees Rex from Abby's flat, forcing Abby and Connor to chase Rex across the golf course.

When the original Anomaly in the Forest of Dean reopens and a string of disappearances plague the area, Helen Cutter returns with a warning for Nick Cutter and the team about the deadly, elusive new predator the team are struggling to track: it is not a creature from the past, but from the future. Nick and Helen both want to go on an Anomaly containment mission into the past to stop the future from altering it, which ends in terrible consequences.

As Cutter struggles with losing Claudia Brown and with the other consequences of the failed mission into the past and tries to get the team to see that history has been altered, the team are sent to a shopping mall to contain an infestation of deadly, ruthless Raptors. Arguments among the team intensify when Cutter wants all the Raptors tranquilised and sent back through the Anomaly alive.

Cutter struggles with the arrival of the ARC's new PR guru, Jenny Lewis, who is physically identical to the lost Claudia Brown, yet is temperamentally a completely different person with no idea of her doppelganger; while Connor gets picked up by a beautiful young woman who is everything he is not, but Abby and Rex are both suspicious of her; and Stephen begins seeing Helen again.

When an Anomaly releases a yellow, sulphuric mist inhabited by giant, carnivorous worms on a gleaming new high-rise office block, Cutter and Stephen are sent in to deal with the deadly creatures with Jenny, while back at the ARC, Connor and Abby try and find a fog-battling weapon.

Connor builds the team a new device designed to detect and locate new Anomalies, but the team become doubtful that the device works when it detects no Anomaly when a paintballer is torn to shreds in the luxurious Blue Sky Park resort. The team soon learn that the mysterious predator stalking the Park is a powerful and deadly sabre-toothed cat, and the race is on to find who is harbouring and protecting the sabretooth before it kills again.

When a boy's disappearance down a drain coincides with an underwater Anomaly, Stephen and the ARC search the local canal for the aquatic predator behind the disappearance, while Cutter is convinced the creature is somewhere else. Cutter turns out to be right in the worst possible way when Abby is taken by Mer Creatures from the future and held captive in a flooded warehouse cellar. Meanwhile, Cutter and Connor learn that there is a conspiracy within the ARC.

When a young London girl chases her dog through an Anomaly into a harsh, prehistoric desert world, Cutter and Stephen go through on a rescue mission for the girl, but find themselves up against giant sand scorpions. The team's problems only worsen when the Anomaly closes on the trio and leaves them marooned in the hostile desert world.

The team are sent to deal with a Columbian Mammoth rampaging on the M25, and attempt to save a trapped motorist before she frightens the Mammoth into attacking again. Meanwhile, Connor and Abby search for the missing Rex and Caroline, and Stephen reveals his alliance with Helen Cutter. Connor and Cutter spring their trap to find the traitor in the ARC, and Oliver Leek's true colours are exposed and the team race to track him down.

While Stephen deals with a Silurian Scorpion attacking a popular beach resort, the team are trapped in Leek's bunker with an army of creatures. When the creature army escape and run amok in the bunker, the team must both escape the overrun bunker with their lives and stop the creature army from escaping onto the modern world.

The team investigate when an Anomaly opens in an Ancient Egyptian artefact at the British Museum, and when a Pristichampsus comes through, Cutter, Abby and Jenny are sent into a race after the giant crocodilian through Central London. Meanwhile, Connor and sparky Egyptologist Sarah Page discover that the Anomaly, the artefact and the creature hold an incredible ancient secret.

Cutter's new Anomaly predictions lead Jenny, Connor and Abby to a reputedly haunted abandoned house, where they soon learn that the Anomaly incursion dates back fourteen years and the house is inhabited by a deadly Camouflage Beast. The team also have to deal with the antagonistic suspicions of Detective Constable Danny Quinn on their interest in the house.

Cutter and the team head to a hospital to deal with an Anomaly and a Diictodon colony wreaking havoc on the hospital's power supply, and also have to help deliver a baby and stop a greedy journalist from getting proof of the creatures. Meanwhile, Helen Cutter and her clone army launch their attack on the ARC, and Helen reveals a secret about the future to Nick.

As the team emotionally struggle to recover from the aftermath of Helen's attack, Jenny leads the team to a new Anomaly at an airport; where a Giganotosaurus or "G-Rex" threatens the crew of a Boeing-747, a news crew are attempting to document the incursion for the media, and Danny Quinn gives the reluctant team his unwanted help.

Jenny and the team, with unwanted help from Danny, attempt to stop London from becoming engulfed by a pandemic when they face an incursion of a deadly, fast-spreading fungus from the future that turns its hosts into primal monsters. Meanwhile, Sid the Diictodon has escaped Connor's custody into the ARC and is causing calamity, and Jenny learns the truth about Claudia Brown.

When Johnson takes Lester's control over the ARC, the team are forced to flee into hiding from Johnson's forces at an abandoned rural military outpost, where they come under attack by a pack of bloodthirsty Terror Birds.

Danny and the team face a Medieval-esque incursion when a Dracorex comes through an Anomaly pursued by a Medieval knight, who - believing he has followed the creature into Hell - causes calamity around modern London as the team try to reason the truth to him. Meanwhile, Connor tries to buy Rex back from Jack's greedy friend.

Jack searches for answers about Abby's secret life, and gets chased through an Anomaly by a deadly Megopteran; forcing the team to go through on a rescue mission into the desolate, predator-filled ruins of the future.

While the rest of the team deal with a herd of Embolotherium that threaten a rural racing campsite, Danny goes on an infiltration mission to rescue the mysterious Eve from Johnson's forces. But when the team soon discover who Eve really is, her rescue from Johnson has disastrous consequences.

While Sarah and Becker deal with a Megopteran attack at Johnson's old HQ, Danny, Connor and Abby return to the future to stop Helen; the trio soon learn the truth behind Helen's master plan, and are sent on a race through the Anomalies to stop her before she ends humanity at its beginning.