As soon as the car stopped, something did not seem right. Before their seatbelts were even off, another vehicle, a silver Citroen Picasso, parked up in a hurry alongside the foster carer’s car. There was a female in the driver's seat of the Citroen, and a man emerged hurriedly from the back seat. In a matter of seconds, the stranger was outside the car, something silver and shiny in his hand, a knife…