Child abduction is very rare - and when other children are responsible it can be particularly hard to comprehend. So when police in Newcastle upon Tyne were told that a missing toddler was last seen talking to two teenage girls, one notorious case from the 1990s immediately came to mind. As the kidnappers crossed the city, police used hundreds of CCTV cameras in a desperate hunt for the missing girl. Andrew Bomford tells the inside story of what happened.