In the fourth episode, Dromaeosaurs stalk a hadrosaur herd as they cross a freezing river. Male Ornithomimus raid rival nests to bolster their own. Olorotitan raise their offspring on fertile volcanic fields but contend with biting mosquitoes.
Troodontids hunt mammals flushed out by a forest fire. A juvenile Antarctopelta scours the forest for a new winter den. Within the snow-covered forest, a tense standoff develops between ancient rivals, Pachyrhinosaurus and Nanuqsaurus.

In the far north of our planet lies the largest land habitat on earth, home to snow-covered forests and the icy open tundra. These are lands of extremes that push animals to their limits: in winter they are so cold that much of the ground has remained frozen since the last ice age. To stand any chance of survival, animals must adapt in extreme ways: here a super pack of wolves, 25 strong, has come together to take on the only large prey available to them in winter, American bison.
On the featureless tundra, an Arctic fox must strike a living alone. She is a wanderer and will roam many hundreds of miles searching for tiny lemmings, hidden deep underground. The only way to reach them is with a head dive. In the remote far east of Russia, a rare Amur leopard prowls the seemingly empty, snow-covered forest. With little prey available, it must use its ingenuity to find a meal. It follows crows in the hope of finding carrion, but it must not stay long, for it shares the forest with a far larger but equally hungry big cat, the Siberian tiger.
As spring arrives, the forests begin to thaw and life returns. Beneath the ground, a nest of tiny painted turtle hatchlings now emerge, having remained frozen in a state of suspended animation throughout winter. To the north, it is a further month before the sun’s warmth baths the frozen ground of the tundra. Tucked away underground lies a tiny snow queen – a Lapland bumble bee. She is the sole survivor of her colony - the rest perished in the winter freeze - but her larger size, her furry body and antifreeze in her blood have allowed her to survive. Now she is in a hurry. She must feed herself and raise a brood in the brief window of summer while the flowers are in bloom.
Snowy owls also use the open tundra to breed: one pair have raised a nest full of fluffy chicks. With 24-hour daylight in which to hunt, the dedicated parents bring back meal after meal for their ever-growing brood. But one day, they return to find the nest empty.
Today, the biggest challenge in the tundra is climate change. Warming summers are melting the permafrost deep within the soil, causing the ground to thaw and, in places, the land to collapse. These changes are impacting the animals too. Caribou arrive in herds of 200,000 individuals to raise their calves in the rich pastures, but warming means mosquitos emerge sooner and bother the calves before they have had a chance to gain strength. The parents drive their young to cooler, mosquito-free land, but to get there they must cross rivers running with increased meltwater and escape hungry grizzly bears. They, like much of the tundra's wildlife, are adapted to live in the extremes - but the challenge of today’s warming climate could be one extreme too many.

When he killed Mehmed’s messengers, it was a message from Vlad Dracula that he would not pay his yearly dues anymore and it was clear that Vlad wanted a war against the Otoman Empire. Mehmed II sends Mara to coax Hungarian King Matthias Corvinus into an alliance. Vlad Dracula’s army was less than 30,000 men, but he invaded Bulgaria and started killing Mehmed’s men in 1462. He stole the Ottomans’ uniforms for his further attacks on the empire. Vlad also destroyed many ports that were under Sultan Mehmed II on the Danube.
Mehmed had to cross the Danube in order to reach the capital city of Târgoviște and defeat Vlad. The sultan faced the challenge of transporting 100,000 men across the river. Along with men, he had to transport cannons and horses too. The first unit to cross the river Danube included Mahmud Pasha, who was the most trusted man of Mehmed II. An epic battle along the Danube River looms, and Vlad has the upper hand.

When Mahmud Pasha and his men were crossing the river at night, Vlad Dracula started his first attack on the Ottomans. However, Mehmed II was smart enough to know that Vlad would be waiting for them. Mehmed II counterattacks Vlad’s army, and we see the first great battle here.
After his victory, Mehmed's troops advance into Wallachia, and Vlad employs guerrilla tactics to weaken his rival. At one point, Vlad Dracula released some criminals with tuberculosis and bubonic plague in order to infect the Ottomans. He sent these infected criminals to the Ottoman camp at night, and it is considered a great tactic by the experts because we see Vlad Dracula practicing biological warfare. Meanwhile, a threat lurks in the imperial palace.

Mercedes' W13 Is put to the test at pre-season tests at Bahrain with Lewis Hamilton and new teammate George Russell behind the wheel. However, the car exhibits an incredibly unpleasant drive with an excessive amount of porpoising. The team has noticed the issue and plans to work on it before further tests commence. However, for Mercedes, the issue seems to remain unfixed. Indeed, the issues are present coming to the races at Imola, Spain, and Monaco, before arriving at the Baku City Circuit for Azerbaijan. Lewis' back starts to exhibit pain as he goes down the straights of Baku as Max Verstappen takes home the victory with Lewis taking fourth. After the race, the team principals convene for a meeting, where Toto Wolff of Mercedes expresses his dismay and concern about the safety of the drivers.
The Silverstone round, which also coincided with Zhou Guanyu's big crash coming into Abbey, finishes with Lewis Hamilton taking third place and Carlos Sainz Jr. taking his first career victory in Formula One. Lewis, having questioned the possibilities of retirement following the 2021 season, announces he is here to stay with Mercedes.

The first outing of the Miami Grand Prix is starting, and Ferrari looks to continue their successful streak starting from Bahrain and Australia into Miami. Ferrari's two drivers Charles Leclerc - who is leading the Drivers' Championship coming into the race - and Carlos Sainz Jr. lock out the first two rows of the grid. In the race, Verstappen immediately takes second from Sainz, and would take the lead by the ninth lap. Soon, McLaren's Lando Norris makes contact with Pierre Gasly of AlphaTauri, bringing out the safety car. Leclerc's old tires soon give him a disadvantage, which Verstappen exploits in his first victory in Miami. Leclerc finishes second ahead of his teammate.
As the season continues, Ferrari continues to make errors that end up costing their drivers the win; in Monaco, Leclerc leads the race as Sainz is brought in - but Leclerc, having been told to come in too, follows Sainz into the pits - only being told to stay out after he had already came in for his stop - handing Red Bull's Sergio Pérez the victory as Leclerc finishes fourth; in Baku, both Ferraris - Leclerc leading - retire due to mechanical failure with Verstappen winning; and in Canada, both Ferraris stay out again and are inconvenienced by their old rubber, handing Verstappen the win once again.
At a rainy Silverstone qualification, Sainz scores his first pole position in his career, and Leclerc, having spun earlier in quali, takes third. The race starts with a big crash for Zhou Guanyu, red-flagging the race. The race starts with Sainz, having retained his grid position, getting a good start; by lap ten, Sainz continues to control the field, but makes an error, allowing Verstappen to take the lead. However, the Red Bull driver reports a puncture and pits, allowing Sainz to take the lead again with Leclerc behind. Soon, the Ferrari pit wall tells Sainz to give the position to Leclerc as Esteban Ocon retires due to mechanical issues, bringing out a safety car. As Leclerc is told to stay out on his old tires, Sainz is brought in for fresh rubber. The race restarts and Sainz overtakes his struggling teammate for first, going on to win his first race in his career. Mattia Binotto, acknowledging the strategical errors made throughout the season thus far, resolves to fix them in the following races.