Cannabis is the world's favourite drug, but also one of the least understood. Can cannabis cause schizophrenia? Is it addictive? Can it lead you on to harder drugs? Or is it simply a herb, an undervalued medicine? Addiction specialist Dr John Marsden discovers that modern science is finally beginning to find answers to these questions. John traces the cannabis plants' birthplace in Kazakhstan; finds the origins of our sensitivity to cannabis in the simple sea squirt; and finds out just what it does to our brains. He meets people who have been changed by this drug in drastically different ways - from those whose lives have been shattered to those who lives have been revived.

The extraordinary wildlife, culture and history of this immense, fascinating ocean and its myriad islands are revealed in stunning detail. With its coral reefs, turquoise lagoons and dramatic oceanic atolls, the South Pacific is the archetypal paradise. It is still relatively healthy and teeming with fish, but it is a fragile paradise. International fishing fleets are taking a serious toll on the sharks, albatross and tuna, and there are other insidious threats to these bountiful seas. We look at what is being done to preserve the ocean and its wildlife.

On a spectacular journey through Renaissance Italy, Andrew Graham-Dixon searches for the shadowy figure who wrote one of the most important books on art and looks at some dazzling works, including masterpieces of the early Renaissance by Giotto, Masaccio and Donatello. Giorgio Vasari was the grandaddy of all art critics, travelling Italy in the 16th century for his definitive Lives of the Artists. It was a time of miracles that he named 'the Renaissance'.

Andrew Graham-Dixon retraces Vasari's footsteps for this captivating two-part film in a short Art of Italy season. He's an enthusiastic guide, lapsing easily into Italian conversation with the custodians of galleries and chapels who allow him a private view. From Brunelleschi's Duomo in Florence to less familiar marvels - a Donatello sculpture; Masaccio frescoes - he illustrates how rapidly ideas developed. A final treat for him - and us - is a tour of the Vasari Corridor, a rarely accessed gallery that zigzags across the Florentine rooftops.

Black Holes are one of the most destructive forces in the universe, capable of tearing a planet apart and swallowing an entire star. Yet scientists now believe they could hold the key to answering the ultimate question - what was there before the Big Bang? The trouble is that researching them is next to impossible. Black holes are by definition invisible and there's no scientific theory able to explain them. Meet the astronomers attempting to image a black hole for the very first time and the theoretical physicists getting ever closer to unlocking their mysteries. It's a story that takes us into the heart of a black hole and to the very edge of what we think we know about the universe.

'In Search of Beethoven': takes a comprehensive look at the composer's life through historical research and Beethoven's biography and letters, but with the emphasis always on the performance -- and interpretation -- of Beethoven's music. From his early piano concertos through the "Moonlight Sonata," "Für Elise," and the immortal notes of the Fifth and Ninth Symphonies, Beethoven's music remains as beloved, popular, and relevant as any work of art has ever been. "In Search of Beethoven" brings together the world's leading performers and experts on Beethoven to reveal new insights into this celebrated composer.