What makes a story engaging? It’s something I’ve been wondering as I make my way through Samuel R. Delany’s Babel-17. It’s a science-fiction novel from 1966 about a young linguist, Rydra Wong, trying to decipher the language – codenamed ‘Babel-17’ – of an alien Invader. It’s a novel that’s very much focused on ideas and has very little colour. The thing it most lacks, in my opinion, is memorable characters.