In the fourth episode, several women recall their harrowing experiences with one man's heinous attempts at virtual blackmail, aimed at obtaining sensitive sexual material.
A woman tells us: 'I received a message from a man who said: Send me a naked picture or I will kill you'. This young woman was able to add her case to those of other women who were encouraged to denounce and expose the harasser. No one is completely invisible on the Internet.

In the fifth episode we will see from counterfeit Beanie Babies to very real tax crime. One person wonders if could make refunds in the name of dead people. It turns out that it can.
We will also see an attempted fraud by two hackers to the IRS: the United States federal agency in charge of tax collection. These skilled hackers revisit cyber schemes that landed them in the sight of law enforcement.

In this sixth and final episode, the FBI escalates its pursuit of an elusive hacker, but he soon turns the tables by questioning the legality of a key tool in their investigation.
We'll also find out how one man is being watched by the government for alleged Russian election interference. Is he responsible, or just a patsy for more powerful people? We'll have to get to the end to find out.

A young mother's mysterious death and her son's subsequent kidnapping blow open a decades-long mystery about the woman's true identity and the murderous federal fugitive at the center of it all.
It's late at night in Oklahoma City, in April of 1990. Two or three guys are in a truck driving along the road and they see some kind of debris. And then they see off to the side, there's a body. It appears to be a young woman, a blonde-haired woman and they call an ambulance. She's rushed to the hospital, and her husband, Clarence, eventually shows up. He says her name is Tonya Hughes, that she's a stripper in Tulsa, and that they have a young son named Michael. And he's much older and he's just kind of this weird guy. So, the doctors, as they continue to examine her, they see old bruises and old injuries. There's something wrong with this picture. Ultimately, she passes away. The girls Tonya danced with want to find her family. So they call this woman and they tell her that her daughter died. And she says, 'What are you talking about? My daughter died 20 years ago, she was only 18 months old.' They realize that who they just buried was not Tonya Hughes, so now they're asking, 'What happened?'.

At the top of our planet lies a magical realm, the Arctic Ocean. After four months of winter darkness, the sun returns to reveal a frozen ocean covered in ice. Mother polar bears emerge from their hillside dens and lead their cubs down to the sea ice to hunt, while a young male and female bear forge a surprising friendship out on the ice.
For others, the frozen sea is a trap. A pod of beluga whales has been confined to an ice hole for five months, slowly starving to death as the food around them runs out. Their salvation lies in the strengthening sun that comes with spring, melting the sea ice, allowing their escape.
Off the east coast of Greenland, the floating pack ice in spring is a nursery ground for harp seals. Mothers and pups have just a few weeks together for the pup to learn to swim before she leaves him to fend for himself. But in today’s warming climate, storms can tip helpless youngsters into the sea before they are strong enough to fend for themselves.
Summer is a time of plenty in the Arctic Ocean as plankton blooms feed millions of tiny mouths, such as bizarre skeleton shrimps, as well as the biggest: bowhead whales. These ancient and long-lived whales arrive en masse every year at secret locations known as whale spas. But today, with the loss of summer sea ice, their peace is shattered by orcas from the south. These daring predators are bold enough to take on the much larger bowheads, targeting their vulnerable calves.
The 24-hour daylight of the Arctic summer attracts visitors from afar, including huge flocks of seabirds like crested auklets. A male must use both his song and a secret tangerine perfume if he is to attract a mate. For the resident walrus, the summer heat can be unbearable. After hauling himself to the beach to moult, an old male uses an ingenious technique to get himself back to the cool of the water - a roly-poly!
Summers in the Arctic today bring record-breaking heat. With climate change, it is warming faster than anywhere else on Earth. It is predicted that the Arctic Ocean could become ice-free each summer by 2035, raising new challenges for polar bears. Without sea ice, more and more bears are becoming stranded on remote Arctic islands. It's a dangerous place to be for a mother bear with cubs, surrounded by larger, predatory males.

Voyager, the most ambitious space mission in history. They're the first probes to truly explore half the planets in our solar system: Jupiter, Saturn, Uranus and Neptune. These went from dots of light in the sky, to real worlds. The Voyager missions have ventured far beyond where other probes have explored. They're the first spacecraft to taste interstellar space, exploring further than any human made spacecraft has gone before. They are the greatest space mission ever. The legacy of Voyager is our remnant, it is our memory. It is a sampling of humanity that is out there now among the stars. And if they last until the death of the Universe, as the final stars fade, and everything goes dark, they will be humanity's final statement: ‘We were here.’
In the last episode of the season 10, experts explore the ultimate, ongoing mission of the Voyager spacecrafts.