This week we delve into the least clandestine tool in a spy's arsenal - OSINT. From newspapers and research papers to the rise of social media, open source information has long been the backbone of intelligence gathering, and never more so than now. How did OSINT evolve, how important is it and what does it mean to personal privacy? And how was OSINT instrumental in a mysterious phone call David received while walking over Sydney Harbour Bridge? You may want to have a good think about what you share on line after this!