He goes back to the park to serious trouble among the Tyrannosaurus: Matilda has broken into Terrence's enclosure: Terrence has refused to allow his sister to intrude on his territory and a fight has broken out, in which Matilda is gaining the upper hand. Terrence has been badly bitten about the face. Bob has drug-darted Matilda, but these drugs take time to act on reptiles. When Terrence is badly injured by his sister, Nigel arrives in a roofed jeep and encourages her to chase his jeep. When he comes to dense woodland, he can drive no further and climbs a tree. Matilda pulls the cloth cover off the top of the jeep, and then collapses due to the tranquilliser.
The injured Terence is in good hands, so Nigel, with assistants, drives in the jeep through the time portal to Upper Carboniferous Arran, where the land is covered with coal forest. He had aimed at an island of dry land, but drives out of the Time Portal's field into a swamp over his jeep's axles. The jeep's engine gets wet and stops and will not start. The forest is very quiet, as there is no bird song or tree-frog noise, only wind and insects. A Meganeura flies over.In the park, Terrence is in the animal clinic, anaesthetized, and Susanne is operating on the wounds. She prefers absorbable sutures to surgical clips, since Terrence would need to be anaesthetised again for the clips to be removed. She sews the wounds with the skin edges sticking out a bit, as is sometimes done when operating on reptiles.
On site, Upper Carboniferous air is 35% oxygen, not 20% as now, and that is why the insects are so big. Nigel climbs a 150-foot-tall tree (Sigillaria or Lepidodendron or similar): it has no branches until near its top, and he must use a loop of strap around himself and the tree, to climb. He reaches its top and sees a wide view, and patches of open water: the place to look for Meganeura. A Meganeura flies over.
In the park, an enclosed building to contain a 35% nitrox atmosphere for the coal forest wildlife is being built, with airlock doors. A titanosaur goes past, knocks a partly-built wall down with its head, looks at the rubble, then goes away. Bob says that the titanosaurs cannot seem to settle in one area. Bob offers the titanosaur a cycad leaf, but it does not eat.
On site, Nigel wades through a swamp. Something big moves about underwater and makes bubbles. Nigel hears something big moving about in undergrowth on land, and chases it, and finds an Arthropleura . It rears and confronts him. It is 10 feet long and has big dangerous-looking mandibles. Some modern millipedes can squirt cyanide, which smells of almonds, and Nigel fears that Arthropleura may also.
In the park, Susanne has put climbing poles in the Smilodon enclosures : this is environmental enrichment, which will hopefully make them happier so she will be more accepting of the male.
Bob suspects that the titanosaurs are looking for stomach stones, and collects stones for them.On site, the Arthropleura has gone, leaving a track. Nigel says that that may be the same track that he saw fossilized on modern Arran. He sees two male Meganeura have a dogfight. Afterwards, one flies away and the other looks for food. Nigel has a butterfly net, but a butterfly net big enough to catch a Meganeura is cumbersome. As Nigel makes a move to catch a Meganeura, something in the water bites his right ankle. He says "Animal bites for us wildlife folks are just a badge of courage." They look for a dry area to camp. Evening is coming. The crew camp for the night. They have head lights strapped to their heads. Nigel warns them never to walk without boots on in case of stinging animals. Someone by force of habit puts mosquito net up, and Nigel tells him to take it down, as mosquitoes have not evolved yet. Nigel sleeps under a waterproof sheet in a hammock slung between two giant lycopsid trees in the coal forest. There is a thunderstorm in the night.
In the park, Bob brings a wheelbarrow full of the stones to some titanosaurs; one of them investigates it.
In an observation enclosure, Terrence is lethargic, and blood tests show Susanne that Terrence has septicaemia, and she reluctantly gives himantibiotic (not knowing how the drugs will react with a prehistoric reptile). While it is risky giving antibiotics to an unknown species, Suzanne knows if she does not, the infection of his injuries will probably kill Terrence.
On site, the thunderstorm stops, and it is still night, and animals tend to become active after rain. Nigel goes about with a large ultraviolet light. He finds a Pulmonoscorpius nearly a meter long, by its shell fluorescing. He films it, but his camera work is shaky and he would need the team's cameraman to take good footage. The Pulmonoscorpius then begins crawling onto Jim's bed, and looks as if it may sting him when he twitches in his sleep. Nigel grabs it by the tail end, and it nips him with its pincers. He lets it go away from the camp. This wakes Jim, and Nigel explains to Jim what happened.
In the park Sabrina, the female Smilodon seems happier, and as if she will accept the male. Susanne wonders whether to raise the door between their enclosures.On site, Nigel tries to catch a Meganeura by a technique known for catching modern dragonflies, by filling a long two-handed hand-pumped Water Pistol with detergent solution to squirt on a Meganeura so that it will fall in the water and become wet, so it can be caught easily. The Meganeura are very fast and agile, but after many failed attempts, he hits one perched on a floating log. Nigel gets his net and catches the Meganeura. In the water he sees a big amphibian. He passes the net with the Meganeura in to a companion and swims underwater (without a diving mask) and catches the amphibian after a struggle, as it is very strong and slippery. He shows that it is an underwater ambush predator. It has two rows of teeth in its upper jaw and one in its lower jaw. He sees that it is a Crassigyrinus, whose fossils have only been found in Scotland; he nicknames it a "swamp monster" as it has no common name. That is what bit his ankle earlier. He has to let it go, as he has no way to transport it safely. He holds the Meganeura vertically by its thorax so its wings fan his face, as the forest is very hot and damp, then puts the Meganeura in a net cage.
In the park, Susanne lifts the door between the Smilodon enclosures. They have a water jet ready to separate the two if they fight. The male goes into the female's enclosure. They growl somewhat at each other, but do not fight.
On site, Nigel looks for the Pulmonoscorpius. He finds one nearly a meter long under a half casing of a rotted-out fallen lycopsid log. It has thin claws, so Nigel is worried, because with scorpions small claws mean big sting. He holds its attention with a thin stick and works his a hand behind it and grabs its telson just in front of its sting. As he puts it in a dog carrier, it stings the back of his right hand as he lets it go. But a worse danger is coming.
In the park, Bob has filled the insect house with 35% oxygen atmosphere and has realized the resulting increased fire risk. He lights a thin piece of wood to show the fire risk.
The lightning storm has started a forest fire, which is spreading fast towards them, and in the 35%-oxygen air vegetation is much more inflammable than in modern air. They run towards the jeep. Nigel trips over a big Arthropleura hidden in ground litter. It rears to confront him. Nigel, who was wanting to get away quickly, was not thankful for this delay, but says he must rescue it, else it will be burned alive. After a struggle, he and another man wrap it in a plastic sheet and tie red cord around it. They load everything on the jeep and set up the Time Portal just in front of the jeep, whose engine still will not start. Nigel runs through the Time Portal, comes back with the end of a tow rope, and ties it to the jeep, which is towed out of the coal forest swamp back into the modern age. They see that the tow rope was being towed not by a towtruck or other vehicle, but by a titanosaur, which Bob was enticing with the wheelbarrowful of gastrolith stones. (This seems to imply that someone went back through the Time Portal earlier to tell the park staff to arrange a tow.)
The Arthropleura, the Meganeura, and the Pulmonoscorpius are put in the high-oxygen building. Terrence is recovering well from his injury and infection but wrecks Suzanne's surgery once he wakes up from anaesthetic: Susanne had not restrained him, not realising he would come around so fast. Terrence is taken back into his enclosure, since he seems likely to make a full recovery. Nigel's sting site has swollen but still shows no serious symptoms, so either the Pulmonoscorpius's venom does not affect mammals (it came from a time before mammals), or it did not inject any venom, or he pulled his hand away before it could inject. Bob seems to take a liking to the Arthropleura and hand-feeds it ferns. He says that he likes it because "it isn't some kind of creepy-crawly bug, it's more like a proper animal."