Uncharted: The doctor will see you now

Hannah Fry explores two tales of data and discovery. Two couples are brought together by a tragedy and a tatty piece of paper, which reveals a serial murderer hiding in plain sight. And, across the world in Singapore, a metro system is misbehaving wildly. The rail engineers and company officials are flummoxed. Can data save the day? Produced by: Ilan Goodman and Lauren Armstrong Carter