As a storm builds over the lush plains of Botswana, a single mother frets.
Her name is Ma di Tau, a lioness on the African savannah, and it has been weeks since an invading pride mortally wounded her mate. After ending the head lion's long reign, the rest of the pride has been hunting Ma di Tau's cubs to try to wipe out his bloodline.
As massive, invading male lions and a rival lioness, Silvereye, stalk the family, Ma di Tau tries to travel with her cubs, when suddenly they fInd themselves surrounded by crocodile-infested waters.
These are just some of the incredible moments award-winning filmmakers Dereck and Beverly Joubert captured on camera for their latest documentary, "The Last Lions," which is slated for release in January 2012. It not only includes some of the most spectacular wildlife footage ever filmed, but also a fascinating love story that the audience never sees: the one behind the camera.
Watch "Nightline" anchor Bill Weir's report on "Nightline" tonight at 11:35 p.m. ET.
The Jouberts are big cat conservationists and partners in every conceivable way. Almost every day for the past 30 years, these high school sweethearts have been alone together in the wild.
"The longest we went without seeing anyone at all is 270 days, I think," Dereck Joubert said.
A lifetime ago, the Jouberts left bustling South Africa in search of adventure, became smitten with big cats, and never came back.
At the break of dawn every day, the couple loads up their four-wheel-drive office and takes the swampy commute across the Okavanga Delta in search of clues that will lead them to lions. Along the way, they pass monitor lizards, and move around yawning hippos and adorable baby elephants.
After spending decades on the African savannah, the two have learned that every bird call has meaning and every moving shadow makes sense. They work with the quiet patience needed to capture Ma di Tao and her cubs on the run from the rival pride and dodging hungry crocodiles.
"Nightline" was invited along on the couple's travels through Botswana, following Ma di Tao as she was forced to swim after cape buffalo and escaped some of the world's most muscular lions. To the Jouberts, each of these animals has a soul and a name.
"I think, too often, people see lions as these ferocious beasts, whereas here they realize that they, too, have struggles," Beverly Joubert said. "It really is the story of a working mother."
Every image the Jouberts' capture is intended to create a global uproar, because the animals they are filming are, quite literally, the last lions. When the Jouberts were born, they said, there were 450,000 lions in Africa. Now, they said, there are less than 20,000. Each year, 600 lion hunting licenses are sold in Africa and 556 of them go to America.
"We think that these wild lions will be extinct within 10 or 15 years, that's the number," Dereck Joubert said.
The Jouberts believe it is vital to change people's thinking about how important it is to protect lions, and that shooting the last of the 20,000 left would be a grave tragedy.
"We have to turn safari hunting into a sport that is purely taking a camera and seeing what you can capture, because if we don't, the images that we have are going to be the last of the species," Beverly Joubert said.