The film examines strange shapes of the universe, such as the 'Eye of God', the hexagon on Saturn, and the 'face' on Mars. One of Saturn's moons is a Star Wars lookalike. Could the strange patterns of the universe now solve mysteries that have haunted mankind since ancient times?

In this programme, Mary descends into the city streets to discover the dirt, crime, sex and slum conditions in the world's first high-rise city. This Rome is not the marble Rome we know, but a vast, messy metropolis with little urban planning, where most Romans lived in high-rise apartment blocks with little space, light, or even sanitation. Forced outdoors into the city streets, she reveals where they went to hang out, get drunk, have sex and get clean. She looks at the Forum as a place of gamblers, dentists and thieves, and she explores the lustiness of Roman bar life and jokes. Finally, exploring law and order from the bottom up, Mary examines how this city really worked. She meets Ancarenus Nothus, an apartment dweller who lived in fear of the rent collector; Notorious Primus, who wrote about his three great pleasures in life - baths, wine and sex; and Unlucky Doris, a seven-year-old girl killed in one of Rome's many fires.

Few sounds are more beautiful or moving than the underwater songs of the humpback whale. Male whales compete with their songs, which often last for 10 minutes at a time, and can be repeated for hours on end. Whales separated by thousands of miles of sea will sing almost identical songs. Researchers have found that the songs change throughout the breeding months, following a mysterious pattern repeated across the waves. Whales also use sound to hunt. To catch herring, humpback whales release a stream of bubbles to form a shimmering, circular fishing net. Emitting a repetitive loud scream, they scare the fish into a tight ball, then lunge out of the water to swallow the shoal whole. Now it seems that the long-held image of the gentle giant must change to one of a ferocious and opportunistic hunter.

It's this moment where now both sides realize that no quarter will be asked, and no quarter will be given. Surrender is no longer even an option. You're in this to the end. You either die or you triumph, and there is no other alternative. Amid a spiral of brutality and low morale, Mehmed makes Giustiniani an enticing offer. The grand vizier urges Mehmed to seek a truce with his rival.

The Red Sea is one of the youngest oceans in the world and one of the warmest. The northern region, with its diverse array of marine life, is one of the most visited dive locations on earth while the southern end remains virtually unexplored. It's a global hotspot for marine biology and an important trade route throughout human history, linking the trade goods of India and the Far East with the markets of Egypt and Europe.

Dr Chris van Tulleken, Dr Hannah Fry and Michael Mosley examine the latest research and explore some of the big questions about Covid-19 and the pandemic it has created. Michael visits the UK government's high-security laboratory Porton Down, where vaccines are being tested. He also uncovers what the experience of the 2002 SARs epidemic reveals about this one. Both were caused by coronaviruses, but certain key changes to today's virus have allowed it to infect the world, where SARs was contained.