In the park, there are now more than 24 animals. The two juvenile Tyrannosaurus often threaten each other. There is a heat wave and Martha the mammoth with her small ears and long hair and blubber is affected by the heat, as she had been brought from an Ice Age winter.
Nigel and four other people go on foot through the time portal to the site. A large threatening volcano stands over the area. There are hot springs, and a risk of natural carbon dioxide seepage. There is a small earthquake. They get away onto higher ground.
They come to an apparently non-volcanic lake. Pterosaurs fly in and fly with their lower jaws skimming in the surface of the lake for fish. When they get back to camp they find that something had raided their camp and torn much of their equipment apart looking for the meat that was part of their rations. This loss of food supplies causes a crisis. As they walk through a forest, something follows them through the fern undergrowth, then goes away.
In the park, Martha the Mammuthus is led to stand between two jeeps, and several members of the team stand on one of them to clip her hair short to avoid the overheating. During this Martha sneezes over everybody and the camera.
On-site, four Mei long attack one of the party, who gets them off him by jettisoning his pack, which contains the meat which they were after. Due to the nature of the attack, it is implied that the Mei long were responsible for the destruction and raid of the camp. Nigel finds an Incisivosaurus. It displays at him and then charges, and bumps the camera with its nose, leaving spit and snot on its lens. It has short quill feathers on its arms, too short for flight, and also quill feathers on the sides of the ends of its tail. It was thought that dinosaur feathers first arose for insulation for warmth, then the quill feathers arose for displaying and later got big enough for gliding.
In the park, Bob is looking at the Ornithomimus from a hide and sees that one of the Ornithomimus starts to go off by itself looking in the undergrowth, and there are fears about its health.On-site, Nigel using binoculars sees some Microraptors going in the same direction, and follows them. This brings him to a herd of titanosaurs pushing through the dense forest making a trampled track as if a convoy of trucks had gone that way. That is not a usual habitat for titanosaurs, and it turns out that they are looking for somewhere to lay eggs safely hidden from egg-eaters. 12 Microraptors come: they were after insects disturbed by the titanosaurs pushing through vegetation and tearing up the ground and treading on insect-ridden rotten logs. Nigel tries to catch some Microraptors, but they are all too quick for him.
Nigel makes an enclosure of net, with inside it a hollow baited with insects, as Microraptors can only glide and cannot take off from flat ground. The Microraptors see the insects but mistrust the net. Out of nowhere, two male Incisivosaurus, one chasing the other, run into the net and flatten it and get away. Then the Microraptors land and eat the insects. Nigel runs at them but catches nothing. The men go back through the time portal to the park.
In the park, the one Ornithomimus has started lying about in the shade. Nigel has seen this behavior in birds and guesses that the Ornithomimus is broody.
Nigel and at least four others go back through the time portal to the site. Nigel now has a net gun (which he has tested on Bob), and a carbon monoxide detector. Each man has a gas mask in his pack, as volcanic ash in the air damages the lungs. In a forest, Nigel comes across a pair of Incisivosaurus who seem to be courting, by calling and displaying at each other close up.
In the park, the Ornithomimus is taken into the vet's examination room. A bag is put over its head, to quiet it. Medical ultrasound shows that it has two fully-developed functioning oviducts, each containing an egg. (Modern birds only have a left oviduct.)
The two Tyrannosaurus are threatening each other.
On-site Nigel sees that the titanosaur trail goes downhill towards the volcano, but he must follow it. They find several Mei long which had gone to sleep in a flat-bottomed hollow. Nigel plans to avoid the hollow to avoid waking them, but something seems wrong. He claps a few times, but nothing happens. He pokes one with a stick, but it does not wake. He realizes that the Mei longs are dead from gassing by carbon monoxide of volcanic origin. He looks at his carbon monoxide detector, which gives a reading. He calls out "carbon monoxide!" and tells everybody to go to higher ground.
In the park the two Tyrannosaurus start to fight. They are separated by water blast from a watercannon mounted on a large water tanker truck and put in separate small pens while a partition is built dividing their enclosure. Both growl and roar in frustration.On site, Nigel and his party finds the titanosaurs laying eggs in ground warmed by underground volcanic heat, a good place for incubation. He picks up one of the eggs and puts it back in the nest. Unlike with a hen's egg, it must always be the same way up, to avoid damage to the embryo. He reflects that the hatchling would grow to 30,000 times the weight to become adult. The Microraptors arrive, and with his netgun, Nigel catches 4 of them. The strongest quake yet happens, and the top of the volcano explodes violently with an ash cloud. This spooks the titanosaurs, which stampede. Some titanosaurs are coming straight at Nigel, who curls up on the ground wrapped around the Microraptors until they pass. The Microraptor has a simple broken left forearm bone. The volcano erupts, blasting out a huge ash cloud. The dinosaurs stampede. Nigel and his team put their gas masks on and quickly set up the time portal in the falling volcanic ash. It becomes active just in time, and 10 titanosaurs come through it, surprising the men in the park, who have to find somewhere to put them; Bob says "I don't believe it." seeing them come through the time portal. In the darkness, the other animals, including Mei, have been annihilated.
In the park the broody Ornithomimus starts to lay eggs: it has laid six eggs (one pair per day) in a part circle when the episode ends. The injured Microraptor's arm is splinted under anesthetic; one of the staff refers to it as "she". Bob erects a new fence which he believes will keep the titanosaurs contained: however, the dinosaurs roar to differ...