Carl Dinnen investigates the controversial use by police in Detroit of facial recognition software, which is said to misidentify African-American faces at higher rates than white ones. Tom Clarke travels to Colombia to meet a man fighting to save South America's elusive pink river dolphins from extinction, while Lucrezia Milarini is in Berlin, where the city council has approved drastic measures to curb surging rents. Current affairs programme, presented by Rageh Omaar.