Our blue planet is facing one its biggest threats in human history. Trillions of pieces of plastic are choking the very lifeblood of our earth, and every marine animal, from the smallest plankton to the largest mammals, is being affected. But can we turn back this growing plastic tide before it is too late? Wildlife biologist Liz Bonnin visits scientists working at the cutting edge of plastics research. She works with some of the world's leading marine biologists and campaigners to discover the true dangers of plastic in our oceans and what it means for the future of all life on our planet, including us.
Liz travels to a remote island off the coast of Australia that is the nesting site for a population of seabirds called flesh-footed shearwaters. Newly hatched chicks are unable to regurgitate effectively, so they are filling up on deadly plastic. She visits the Coral Triangle that stretches from Papua New Guinea to the Solomon Islands to find out more from top coral scientists trying to work out why plastic is so lethal to the reefs, fragile ecosystems that contain 25 per cent of all marine life.

Time travel is not forbidden by the laws of nature, but to build a time machine, we would need to understand more about those laws and how to subvert them than we do now. And every day, science does learn more. In this film Horizon meets the scientists working on the cutting edge of discovery - men and women who may discover how to build wormholes, manipulate entangled photons or build fully functioning time crystals. In short, these scientists may enable an engineer of the future to do what we have so far been only able to imagine - to build a machine that allows us travel back and forward in time at the touch of a button. It could be you! Science fiction? Watch this film.

Documentary-maker David Malone delves into the secrets of ocean waves. In an elegant and original film he finds that waves are not made of water, that some waves travel sideways and that the sound of the ocean comes not from water but from bubbles. Waves are not only beautiful but also profoundly important, and there is a surprising connection between the life cycle of waves and the life of human beings.

Lucy Worsley travels to Russia to tell the extraordinary story of the dynasty that ruled the country for more than three centuries. It's an epic tale that includes giant figures such as Peter the Great and Catherine the Great, the devastating struggle against Napoleon in 1812, and the political murders of Nicholas II and his family in 1918 which brought the dynasty to a brutal end.
In this first episode, Lucy investigates the beginning of the Romanovs' 300-year reign in Russia. In 1613, when Russia was leaderless, 16-year-old Mikhail Romanov was plucked from obscurity and offered the crown of Russia. Lucy also charts the story of Peter the Great, the ruthless and ambitious tsar who was determined to modernise Russia at the end of the 17th century.

Comet ISON can well be the brightest and most spectacular comet for a generation. It appeared above the eastern horizon from December 2013 as a glorious streak across the sky. ISON has been travelling towards the sun for ten thousand years and will make only one orbit through its corona before disappearing off into the outer solar system.
But as well as providing a great spectacle, ISON's tail of vaporised gas and water, hundreds of millions of kilometres long, will give insights into some of the greatest mysteries of science; it will help explain the origins of the solar system, whether earth's water was delivered on comets and even whether we are alone in the universe.

Award winning wildlife photographers Jonathan and Angela Scott have travelled the world, always returning home to Kenya. There they introduced the world to the big cats of the Maasai Mara and now they are part of its fight for survival.