The meteoric rise of renewable energy has consequences for our electricity supply. While coal and gas fired power stations can generate electricity whenever you need it, renewables are intermittent by nature. So we need a backup plan for when the wind stops or the sun goes down.
All over the world, engineers and scientists are racing to solve one key problem; how to safely and efficiently store electricity at a huge scale but at a low cost. The quest is producing some truly remarkable ideas and this episode details three of them.

Ewan and Charley make their way to Peru from Bolivia, and the scenery is just beautiful. Ewan wanted to visit Machu Picchu since he was a kid and decides to show the world the Incan citadel set high in the Andes Mountains. Next up, they make their way to the Cutivireni, a community of Ashaninka people in the Amazon rainforest, with its carbon program to limit the magnitude or rate of global warming and its related effects.

The film investigates the inner workings inside the commercial pet food industry, which has went largely unchallenged until now and Pet Fooled is made with an aim to expose its secrets and lack of transparency. Marketed toward humans, but made for consumers who can’t speak, pet food companies have learned how to navigate through verbiage and loopholes. The end result is a product that’s cheap and easy for them to make, while buyers are promised that they’re giving 'quality,' 'healthy,' and 'nutritious' food to their pets. Some veterinary professionals in the film link modern ailments found in pets, such as obesity and allergies, to diet.
Insights and knowledge are shared by multiple interviewees, including Dr. Karen Becker of Mercola Healthy Pets, Dr. Barbara Royal, founder of The Royal Treatment Veterinary Center and Oprah Winfrey’s veterinarian, Susan Thixton, founder of Truthaboutpetfood.com.

More than 2,000 years ago, the thriving city of Petra rose up in the bone-dry desert of what is now Jordan. An oasis of culture and abundance, the city was built by wealthy merchants whose camel caravans transported incense and spices from the Arabian Gulf. They carved spectacular temple-tombs into its soaring cliffs, raised a monumental Great Temple at its heart, and devised an ingenious system that channeled water to vineyards, bathhouses, fountains, and pools. But following a catastrophic earthquake and a slump in its desert trade routes, Petra's unique culture faded and was lost to most of the world for nearly a thousand years. Now, in a daring experiment, an archaeologist and sculptors team up to carve an iconic temple-tomb to find out how the ancient people of Petra built their city of stone. Meanwhile, scientists using remote sensors and hydraulic flumes uncover the vast city and its sophisticated water system. The race is on to discover how these nomads created this oasis of culture in one of the harshest climates on Earth.

As they prepare their counterattack against Caesar, Pompey's Republicans begin to squabble over both the anticipated spoils and the method of finishing Caesar off. Badly outnumbered, Caesar and Antony make their stand at Pharsalus. As they try to reach Caesar in Greece, the shipwrecked Vorenus and Pullo confront an unexpected dilemma.
Back in Rome, Atia again sends Octavia to beg protection from Servilia, who complies readily to encourage her growing friendship with Octavia. Niobe's sister Lyde comes back to see her and comforts her over Vorenus's disappearance.

Cicero is finally undone by his duplicity in the form of Titus Pullo, acting upon Octavian's request to assassinate all supporters of Brutus in Rome. Pullo and Vorenus enjoy a happy if counterfeit outing with their families in the countryside to hide their assassin mission.
Vorena the Elder's dangerous dalliance with one of Mimeo's men continues, and the torrid affair between Octavia and Agrippa escalates. Atia's casual cruelty to ask for the assassination of people she doesn't like results in complete disaster for Octavia's friend Jocasta.