Singapore, 2016. A high-tech driverless train system starts glitching in wild and unpredictable ways. The train company, the government, even the military are at a loss: no-one can figure out what is causing the problem. Until Jason Bay and his team of data scientists assemble an old-fashioned timetabling graph, first developed in 19th century France, which exposes an invisible culprit. Behind every line on a graph, there lies an extraordinary human story. And mathematician Hannah Fry is here to tell us ten of them. Hannah Fry tells a tale of data detectives and very naughty trains. Presenter: Hannah Fry Executive Producer: Martin Smith Series Producer: Lauren Armstrong-Carter Episode Producer: Ilan Goodman A series for Radio 4 by BBC Science in Cardiff.