In the park, the dinosaurs are settling in. The Tyrannosaurus rex are being fed. Nigel goes to visit a herd of African elephants in the park: there are at least four including a young calf. He now wants to rescue a woolly mammoth from extinction. He goes through the Time Portal to 10,000 BC northwest Siberia just east of the Ural Mountains where the last mammoths lived. It is early spring but the land is still under snow. He drives a snowmobile over a frozen lake. He sees nothing but dense taiga forest and rocky mountains: as the land became warmer as the Ice Age ended, trees replaced tundra grass and mammoths lost their grazing lands. As they cannot eat pine needles, this reduced their numbers. Then prehistoric Cro-Magnon humans finished them off by hunting them for food. He explores a nearby cave and comes face to face with a muscular male cave bear; he had disturbed its hibernation. He had thought that the cave bear would already be extinct by this point. It chases Nigel and the cameraman away. Without the equipment to transport it safely, Nigel cannot save it, so he decides to get back to saving a mammoth. Nigel goes up a rocky slope to scout the area. He sees what a gap in the trees: it may be open land, and perhaps there are mammoths there. He decides to check. He finds two adolescent female mammoths. The older mammoth is dead in a pit. The younger mammoth makes rumblings in her stomach, trying to communicate with her dead companion. She looks ill. She staggers and falls to the ground. She is so weak that she can barely lift her trunk. She is staying with the fallen mammoth; they may be sisters. Nigel sees a spear wound in her left shoulder. He brings in his team to help. In the park, the Ornithomimus are not eating the grass, nor the beetles living there. Bob realises that they have duck-like mouths: rough likesandpaper. He decides to put them into an enclosure with a pond. The Ornithomimus thrive in their new home. Nigel needs to get the mammoth strong enough to walk through the Time Portal. He gives her an antibiotic injection. Evening comes and the palaeolithichunters are back. The Park men put up a line of big burning torches stuck in the ground. The men plan to guard in turns, but Nigel decides to sit up with the Mammuthus all night, to keep her company. Wolves prowl about at a distance all night. Morning comes and the mammoth is strong enough to stand. It shows no aggression, and stays with her dead sister, but the team must get her back to the park. They set up the Time Portal. Nigel leads the mammoth back to the present and calls on a walkie-talkie for urgent medical help. In the park, Susanne gives sedative and antibiotic to the mammoth, treats the wound, and after some pulling extracts a stone spearhead from it. She is on the road to recovery. They name her Martha. Martha is healthy, but is not eating, and needs to eat for strength to recover. They put Martha in an enclosure labeled "Mammoth Mount". Suzanne looks at an African elephant molar and a mammoth molar, and sees that they are designed to chew about the same sorts of food. Maybe Martha is not eating because she needs a specific diet. To solve the mystery, Nigel goes through the Time Portal to the same place in Siberia 150,000 years ago at the peak of the ice age. Mammoths range across from Europe to northeast Asia. He finds a large herd of adult female mammoths. The land is cold but dry and has many kinds of grass and no trees. Each herd follows a matriarch, who is 50 or 60 years old. He collects a large sample of grass and mosses to bring back and analyse. A male mammoth on musth comes, looking for females ready to mate. All the mammoths are thriving on the grassland diet. He sees a sub-adult male Elasmotherium by the snowmobile. It is downwind from him. but there is a risk of it seeing him, and if it sees anything unexpected it may charge. Nigel is between the Elasmotherium and the musth male mammoth. He drops the bag of vegetation and runs to the snowmobile and drives to a safe distance. Nigel decides to bring the Elasmotheriumback, riskily using himself as bait, as Elasmotherium will soon be extinct due to climate change. Nigel runs to the sample bag. TheElasmotherium charges at him. Nigel picks the bag up and runs. The Elasmotherium chases him through the Time Portal into the entrance stockade in the park. Back at the Park, Nigel offers Martha the Ice Age grass, but Martha still refuses to eat. Whilst he admits it is anthropomorphic to say so, Nigel thinks that she looks lonely; in the wild female mammoths are always in groups. TheElasmotherium, which is accustomed to being alone, is settling in but Martha is accustomed to being with relatives. There is a council, to decide on putting Martha with the elephants. It is risky: elephant matriarchs have been known to kill new elephants that tried to push into an established herd but they decide to try it. At Mammoth Mount, the elephants come up to Martha's enclosure. Martha and the elephants' matriarch approach each other, curious, and non-aggressively. Nigel calls to open the gate. Martha follows the elephantmatriarch. Martha is now eating well.

Nigel is shown walking with a tame cheetah. He comments that specialization has threatened the cheetah, and later that specialization may have wiped out the Smilodon. In the park the titanosaurs break their fence and have to be let wander around the park. They go towards the park's main gates. Bob follows one in a tractor. During this he shouts at a titanosaur "Get back, you great lummox." To his disgust it discharges runny smelly faeces in front of him: its gut clearly does not like some of the modern vegetation. At the same time, Nigel radios to Bob that he will need a birdcage for a bird standing 10 feet high, but due to tractor engine noise and titanosaur noise, Bob only hears part of the message, and provides an ordinary parakeet-sized birdcage. Nigel explains to Bob what is needed. Nigel goes through the time portal to South America 1 million years ago when the sabre-tooth species known as Smilodon were in their prime (having recently entered South America after the Panama land bridge formed), but the terror birds (Phorusrhachids) were dying out; before that South America had been cut off from the other continents for 30 million years. He drives through a moving herd of Toxodon; he follows them to find where they were going, and he sees that they were going to water to swim or wallow in: he sees that they lived like modern hippopotamus, and thus may be dangerous like hippos. A huge male Toxodon chases Nigel's jeep, and he has to drive fast and far before it gives up the chase. In the park the female Ornithomimus had laid more eggs. Two of them have rolled out of the nest and she leaves them there, so Susanne must rescue them for artificial incubation, as all those eggs are precious. Susanne stalks up to them and picks them up; the Ornithomimus does not chase, but demonstrates, causing a flurry among some white egrets. Bob puts the 2 eggs in an incubator at 33 °C, as this is best temperature for crocodile and ostrich eggs. On site Nigel sees a female Smilodon stalk aToxodon and then after a short chase, jump on its head and bite its throat to kill it. More Smilodon come, including some 6 to 8 week old cubs. While waiting Nigel has a coffee and the Smilodon eat their fill and go away. A Phorusrhacos starts to eat from the carcass. Another Smilodon appears and chases it away, forcing it to drop a lump of meat which it had pulled off. That sort of pressure is why thePhorusrhacos were dying out. Nigel stalks up to that dropped piece of meat and picks it up. The Smilodon on the kill demonstrates at him but does not charge at him. Nigel tows the piece of meat behind his jeep and entices the Phorusrhacos to chase it through the time portal into the park. In the park the eggs incubated by the Ornithomimus hatch and the resulting young run about (the first baby dinosaurs for 65 million years), but the two eggs in the incubator do not hatch. The young Ornithomimus are covered in downy feathers. Accompanied by big cat expert Saba Douglas-Hamilton, Nigel goes through the time portal to South America in 10,000BC when the sabertooth species were dying out. They find a drier climate and no big game. Nigel and Saba separate, on foot. Saba hears animals' alarm cries, but Nigel finds nothing. Saba finds a deposit of fresh Smilodon faeces. She pulls it apart with a knife and fork and finds that it is full of hair and bone and bits of animal hide, as if hunger had forced the Smilodon to scavenge old remains of carcasses. Nigel hears vegetation noise from an animal near him. He finds, catches and releases an ordinary modern-type armadillo and remarks that a million years earlier there were giant armadillos about. Saba later finds something in the grass; sadly, it is a dead Smilodon cub. Nigel cannot find any signs of ill health and realises that the cub must have died from starvation. This has at least given them a hint. A femaleSmilodon cannot be far away. However, she must be in very poor condition. Nigel has a videocamera with a movement detector: he leaves it overnight watching over a trail. In the morning he plays it back and finds that a male Smilodon had investigated it and knocked it over, urinated on it and left a musky mammal smell. Saba watches the female Smilodon hunting. It sees her and confronts her. She backs off. Nigel meets Saba. Due to lack of prey the female Smilodon is hunting unsuitably light fast prey, a deer: when she charges, the deer runs away easily. Later they see her suckling a live cub, but she is making little or no milk for it. A male Smilodon turns up: there is risk that it will kill the cub to bring its mother into oestrus sooner. In the jeep they anaesthetic-dart the male Smilodon and start to wait 10 minutes while the dart drug works. The Smilodon charges out of bushes and jumps on the front of the jeep; they back off. In the park the men have finished building a partition across the Tyrannosaurus enclosure, and put a Tyrannosaurus on each side. Matilda keeps threatening Terence but now cannot reach him. On site, they find the male Smilodon and load it up on the back of the jeep. Then they go for the female, planning to anaesthetic-dart her and load her and her cub. When they reach her, the cub has starved to death. The female Smilodon is badly underweight from trying to lactate on too little food, and is dying as well, so Saba anaesthetic darts her. A little while later, Nigel and Saba load the female into the jeep, but both are upset that the cub could not be saved. The twoOrnithomimus eggs in the incubator hatch, late but successfully: Bob guesses that the incubator's temperature had been set a little too low. The two resulting hatchlings see Bob and imprint on him, thinking that he is their mother and follow him about. They eat food pellets out of his hand. With good food and no need to lactate, the two Smilodon and the Phorusrhacos recover from their hunger over the next fortnight. However, tensions remain high, as Matilda's increasingly aggressive behaviour could spell danger for the Park.