'Farewell, Great Macedon': The TARDIS materialises in the Hanging Gardens of Babylon, one of the Seven Ancient Wonders of the World, in the year 323 BC. The Doctor, Ian, Barbara and Susan meet Alexander the Great - but their excitement is tempered by the realization that these are the final days of Alexander's life. As the travellers become embroiled in the tragic events, the inevitability of history unfolds around them. But can they - and should they - change it?

'The Fragile Yellow Arc of Fragrance': Fragrance is a paradise world - a utopia that the travellers are loathe to leave after a relaxing stay. But the way of life is different here. And so is the way of love - as Barbara discovers when the Fragile Yellow Arc is broken....

Directed by Lisa Bowerman.