This episode probes the perpetual darkness and reveals the unknown underground world found in caves.

Looking at how the team filmed emperor epenguins and polar bears on the Poles.

Meet a cast of extraordinary animals on a 24-hour journey through the world's jungles.

The Planet Earth team reveal how they filmed a pride of lions hunting elephants at night.

This 'making of' series follows the daring film crews as they brave the elements in the Polar regions.

Japan's largest island is Honshu: home to over 100 million people, this is the historic heartland, and its biggest city, Tokyo, is one of the largest urban metropolises on Earth.

As the days grow shorter in the Arctic, daily tasks become more burdensome.

The ground conditions are extreme as five abandoned engineers seek to build an escape craft out of ship wreckage.

Lucky uncovers the dark truth behind Jeni's activities, but at what price?

Despite a rocky start in Paris, the European tour continues. Next stop: Amsterdam, where it seems that nothing can prevent the family from getting into the holiday spirit.

Massimo,determined to stop Dominic, hacks NYL servers with Subterranea's help to give the media proof of the scandal. But when Massimo and Sofia realize that Duval will use the scandal to his own anarchic interests, they betray him.

Sephy, the Cross daughter of powerful Home Secretary Kamal Hadley, and Callum, the Nought son of their housekeeper Meggie McGregor, reunite, and a spark is ignited.

Marlon is on the edge. April's despair escalates. Bob is uneasy about why Wendy lied to him.

Leyla has some news. April is terrified. Wendy makes an admission.

The police are called to the house of a specialist on the Romantic poets. Dr Stringer thought there was an intruder in his garden, but doesn't have much to steal.

Graham's guests this week are Nicole Kidman, Kylie Minogue, Nicola Adams, Jason Manford, Josh O'Connor, and Emma Corrin.

Gudrun and her friend Frida are playing hide and seek. When they stumble upon a roe deer hiding her kid in the long grass, Gudrun realises what she needs to do to disappear for the game of hide and seek.

Welcome back to more exciting animal guests, and amazing fun facts with Andy's Secret Hideout Series.Andy meets some bright pink flamingos, and tells us some interesting facts about some unique birds from around the world.

Duggee is back with his merry band of Squirrels for more clubhouse adventures. Duggee is not very well, he has lost his voice. The squirrels want to make him feel better.

Tee wakes up super-early and wants to play immediately.

Visit the magical Night Garden world with all your favourite friends. Everyone boards the Pinky Ponk for a journey. Where are they going? They are off to see the bud of the Olly Bolly Dob Dob flower.

Bluey, Bingo and Mum are enjoying playing Keepy Uppy around the house with their last balloon, when Dad joins in and the game becomes the ultimate test of skill.

Charlie and Marv have to come up with an invention for a school project by tomorrow. Lola thinks that she's an extremely good inventor too, and keeps interrupting their efforts with ideas of her own.

Welcome back to more exciting animal guests, and amazing fun facts with Andy's Secret Hideout Series.Andy tells us about certain animals that are great at camouflage.

Meet Duggee and his merry band of Squirrels! The squirrels do such a good job making sandcastles that they are asked to help the crabs build a new home.

The Clangers are curious creatures who live on a small blue planet, out in the starry stretches of space.Major invents a system so he can hear the other Clangers when they call him for soup.

Full steam ahead for new adventures with Thomas & Friends.Paxton overhears Toby say that Thomas has 'lost his puff' after he accidentally gets his firebox wet.

Join in the fun with Ruff-Ruff, Tweet and Dave as they go on magical adventures. Ruff-Ruff, Tweet and Dave compete as 'Team Hilltop' against 'Team Jungle' in some fun sporting challenges.

A cheeky monkey called Mr Ook Eek checks into the hotel. Elmo suggests they show Mr Ook Eek the surprise they've put in the garden for him - a tyre swing.

In a game of 'Work', Dad hires Bluey and Bingo at his drainpipe factory.

Thomas, Annie and Clarabel have to deal with a noisy baby.

It's a big day for a parasaurolophus family as they try out their loud trumpets.

Tee and Mo follows the daily adventures of a funny and precocious little monkey, Tee, and his clever and unstoppable mum, Mo.

Meet Nelly and Nora! Two young sisters who love to explore the outdoors, whatever the weather. It's a very windy day and Nelly and Nora have to work together to get home.

Duggee is back with his merry band of Squirrels for more clubhouse adventures. It is a lovely day and the Squirrels are playing the shape game outside. Working out which shape goes where is quite tricky.

Come on a curious adventure with Sarah and her quacky, flappy best friend, Duck. Sarah and Duck try to help Donkey get his jumping confidence back.

Visit the magical Night Garden world with all your favourite friends. Upsy Daisy wants to rest in bed but keeps being disturbed.

Clangers are pink, long-nosed creatures who live on a small blue planet. Small, Tiny and Baby Soup Dragon have a race around the planet, but Baby Soup Dragon cheats so he can win.

Numtums are ten cuddly creatures with numbers on their tummies, who love to count! Numtum number five DJs for her number five party in her butterfly wings.

Andy travels back 220 million years to the era of the Postosuchus - a giant creature that roamed North America in the time of the earliest dinosaurs.

Xuli and Foz are on a holiday adventure, cracking clues to find Xuli's long-lost friend.

Join in the fun with Ruff-Ruff, Tweet and Dave as they go on magical adventures. Ruff-Ruff, Tweet and Dave compete as 'Team Hilltop' against 'Team Jungle' in some fun sporting challenges.

Come on a curious adventure with Sarah and her quacky, flappy best friend, Duck. Sarah's hat goes on an adventure without her, on top of a balloon.

The adventures of magical Baby Jake and friends. Baby Jake and Nibbles the rabbit go on an orchard adventure and try ballet dancing.

Bluey, Bingo and Mum are enjoying playing Keepy Uppy around the house with their last balloon, when Dad joins in and the game becomes the ultimate test of skill.

Duggee is back with his merry band of Squirrels for more clubhouse adventures. The squirrels are out on a walk when they come across Tino and Eugene having a disagreement about an amateur dramatic show they want to stage.

Come on a curious adventure with Sarah and her quacky, flappy best friend, Duck. Sarah's zip has broken on her coat and she is sad, so Sarah & Duck visit Scarf Lady to see if she can help.

Get ready to join Andy for some amazing safari adventures! Andy travels to the Namibian desert in Southern Africa to track down some giraffe thorn tree seeds.

Play, learn and laugh along with a quick quiz from the Spot Bots. Watch closely as Pompaloo and Pedro perform a magic trick. Can you spot what has disappeared from the magic table?