Fathom is a visual and aural wonder of a documentary that follows researchers working to finally decode the communication of humpback whales. Dr. Ellen Garland and Dr. Michelle Fournet embark on parallel journeys on opposite sides of the world, as they seek to better understand whale culture and communication. The film uniquely reveals a deep commitment and reverence to the scientific process and the universal human need to seek answers about the world around us.
From hypothesis to groundbreaking experiences in the field, 'Fathom' showcases the passion, curiosity, collaboration, perseverance and work it takes for leading scientists to make scientific discoveries.

Whales have long been a profound mystery to us. They live in a world so removed from our own that we can barely imagine their lives. Their environment is different, their senses are different, their relationships are different. How might such almost alien creatures see the world?, Narrated by David Attenborough.

Horizon discovers what your cat really gets up to when it leaves the cat flap. In a groundbreaking experiment, 50 cats from a village in Surrey are tagged with GPS collars and their every movement is recorded, day and night, as they hunt in our backyards and patrol the garden fences and hedgerows. Cats are fitted with specially developed cat-cams which reveal their unique view of our world. You may think you understand your pet, but their secret life is more surprising than we thought.

Reese Witherspoon explains the world of female Macaques, who use sexually ways to ensure their baby monkeys will grow up with strong male protectors. These females have helped to shape one of the most caring primate societies on earth.

There is one miniature fierce queen, hardly bigger than a grain of rice. Enter the fascinating, and sometimes brutal world of honey ants, struggling not just for survival, but power - all in service of their fearless leader, the queen. Her story has it all-- ambition, murder, and a great army of female warriors on the rampage.

One extraordinary family of fish has achieved the ultimate form of gender equality. When it comes to breeding, seahorses do it like no other animal on the planet. Their fierce females refuse to be left holding the baby. So it's the males that carry their brood. In this episode we explore the world of mating seahorses which are the only animals in the world that have a major gender role reversal.