THE PROMISE – Twenty-three years later, over a thousand families are still waiting for news of loved ones lost in the World Trade Center attacks on 9/11. Correspondent Scott Pelley looks at how efforts to search for and identify their remains have never stopped, driven by the promise made by the New York City Office of Chief Medical Examiner. Pelley visits their laboratory, which is using new advancements in DNA research and breakthrough techniques to provide answers for families holding on to hope. This is a double-length segment. Nicole Young is the producer.AUSSIEWOOD –Correspondent Jon Wertheim reports on a phenomenon that has long captured Hollywood: the outsized presence of Australians earning top billings and awards on the American silver screen – in front of and behind the camera. Wertheim interviews Aussie actress Sarah Snook and filmmaker Baz Luhrmann about the country's renowned training grounds for the dramatic arts, their pathways to international theater, film and television and the Australian mindset on stardom. Jacqueline Williams is the producer.BHUTAN –Correspondent Lesley Stahl travels to the remote, Buddhist kingdom of Bhutan, a tiny country that has fiercely protected its unique culture, declaring that within its borders, Gross National Happiness is more important than Gross National Product. But today, the country is facing a crisis – 9% of its population has left Bhutan for higher-paying jobs abroad, so the government has launched a high-stakes plan to help the economy and lure young Bhutanese back by developing an entirely new city from scratch – what the king is calling a "mindfulness" city. This is a double-length segment. Shari Finkelstein is the producer.