On Start the Week Andrew Marr talks to the psychologist Charles Fernyhough about the inner speech in our heads. But what if it's a lone voice? The writer Olivia Laing explores what it's like to be lonely in a bustling city, while the playwright Alistair McDowall explores what happens when you're abandoned on a distant planet with no sense of time. The biographer Frances Wilson writes a tale of hero-worship, betrayal and revenge through the life of Thomas De Quincey, a man who modelled his opium-habit on Coleridge and his voice and writing on Wordsworth. Producer: Katy Hickman.