Episode One: Prehistoric creatures burst through a rip in time and our team find themselves running for their lives from the hungry jaws of a flesh-eating Gorgonopsid.

Nick Cutter is an evolutionary zoologist who finds himself confronted with the subject of his studies in a way he could never have imagined... Prompted by the enthusiasm of his geeky but brilliant graduate student Connor Temple, Professor Cutter and his lab technician Stephen Hart go to investigate strange sightings of an unknown animal in the Forest of Dean. Close by Abby Maitland, a zoo animal handler, is discovering that the forest is also home to the strangest pet she's ever seen. Could a small lizard, picked up by a young boy in the woods, really be an entirely new species? Determined to find out more, Abby and the boy head off, but as night falls the forest becomes a frightening place...

Meanwhile, Claudia Brown, Home Office Civil Servant in charge of investigating rogue animal sightings is hoping Cutter will instantly dismiss the sightings as fakes. Cutter however, is reluctant to oblige. As Claudia suspects, there's more than professional intrigue behind Cutter's investigations; eight years ago his wife disappeared from the heart of the forest, never to be seen again... Can the answer to this mystery still be out there?

Episode Two: Mammoth spiders attack London's Underground, but in the darkness of the tunnels lies something more sinister still.

Cutter starts to suspect that his missing wife Helen knew about the anomaly. While everyone presumes the discovery of her camera, millions of years in the past, confirms her death, Cutter is developing an entirely different theory. But for now, he is keeping his speculations to himself.

Lester is growing increasingly sceptical of 'loose cannon' Cutter, but Claudia defends him as their only expert and Lester reluctantly agrees to keep him involved - for now. Emotions are running high in this shared world of secrets and suspense and everyone is getting a little hot under the collar. While Lester may suspect Claudia has ulterior motives for keeping Cutter on board, Abby is hoping that Stephen might start to see her as more than just the 'animal expert'.

In turn, Connor has Abby in his sights and attempts to win her over with a night's camping to follow up a top 'dinosaur-sighting' lead. However, it turns out to be nothing more than a hoax and his hopes for adventure of a more romantic nature are dashed.

Episode Three: An ancient sea monster attacks two lifeguards in a municipal swimming pool while a mother makes a terrifying discovery when her utility room starts to flood.

Cutter is desperate to make Lester realise the seriousness of the situation, but infuriatingly Lester remains optimistic that this problem will disappear just as quickly as it arrived. But he is out of luck as the arrival of a vicious sea creature (a Mososaur) at a local swimming pool means bad news all round, particularly for a pair of young lifeguards flouting the heavy-petting ban. The boy becomes the Mososaur's next meal and the girl is charged with his murder. When the boy’s regurgitated body is found in a nearby reservoir, Cutter realises they’ve got another prehistoric killer on their hands.

If that were not bad enough, the anomaly which this particular nasty came through is a mobile one, and has moved from the swimming pool to the depths of the reservoir. The team works hard to find and contain it, but how can you plug a leak in time?

Episode Four: When a flock of comical-looking dodos appear through the anomaly, no one realises that they have brought with them a dangerous parasite.

News arrives of a creature sighting in an apartment on a housing estate. Special Forces storm the building, closely followed by Cutter, Stephen and Connor. They burst into the bathroom to find… a python. As Stephen and Abby attempt to bag the snake, Connor asks if he can stay at Abby's house, to which she absent-mindedly agrees.

Meanwhile, inside the Home Office maximum security wing, Helen is being pumped for information about the anomalies by Lester and Claudia. She eventually agrees to tell all to Cutter, but when he is summoned she accuses him of betraying her. However, she also says that a pride of sabre-tooth cats could come through a new anomaly, and that she will take them to it. Tom and Duncan drop Connor off at Abby's flat, revealing they have bugged his bag with a tracking device hidden in a key-ring. Connor makes himself at home in Abby's flat, until Stephen arrives to summon them to the latest anomaly site.

Episode Five: Connor's carelessness reveals Rex's presence, and an aerial anomaly releases a new danger thirsty for blood

When a golfer cuts his hand on a thorn while playing a ball in the rough, he is chased down the green and dragged into the air. Claudia arrives on the scene and instructs Special Forces to seal the perimeter. Cutter and Stephen are waiting to see the victim when Claudia warns them that Lester is getting impatient. From the state of the golfer's body, it looks like another dangerous predator is on the loose. They manage to track down the location of this latest anomaly, but it is in the air. As they ponder how to cordon it off, a Pteranodon swoops through.

Meanwhile, Connor has heard the news and set out for the golf club. In his haste, he left a window open at Abby's and Rex escaped into the back of the car, without Connor noticing. At the Special Forces checkpoint, he gets out and spots Rex on the car roof, then chases him onto the green. The gang shouts to warn him that a Pteranodon is circling towards them, but he thinks he's been rumbled about having Rex. He finally turns to see the beast and runs for cover. Claudia orders the Special Forces to shoot it, but Cutter, adamant that none of the creatures are killed unnecessarily, pushes Ryan to make his shot miss. Connor jumps out of the Pteranodon's way and it disappears. The truth is now out that Abby has kept Rex. Claudia, furious with them all for causing trouble, begins to side with Lester.

Episode Six: The team meets its most terrifying adversary yet - a predator from the future.

At the original anomaly in the forest, the Special Forces find a wrecked metal fence. Something has been through. At the zoo, a strange and horrible creature attacks the lions. Later, something strange watches Abby feeding the elephants. Luckily for her, it moves on to her boss, Tim Parker, who doesn’t fare so well.

At the Home Office, Claudia reassures Lester of Cutter’s capability, while at the university, Helen approaches Stephen: she wants a meeting with Cutter and Lester, and has information on three missing persons linked to a creature.

The blood analysis taken from the lion pen turns out to be part bat and it's baffling the scientists, until Helen informs Cutter, Claudia and Lester of a new creature threat – from the future. She denies knowing how it arrived and wants to help. Back at their house, Cutter questions Helen further about her motives and discovers that she accidentally lured the creature into the present day.