A teenager was followed as she drove towards Milton Keynes late last night.
The 18-year-old pulled over into a lay-by after being tailgated by a white van driver who was flashing he lights along the A421 fom Buckingham.
The man started shouting at the victim to get in his van after stopping between the Windmill Hill Roundabout and BP Garage on the A421 Standing Way.
The teen ran back to her car and drove away to the V6 Grafton Street at around 10.30pm.
The offender is very tall and was wearing dark clothing with a hood pulled over his head.
The victim believes the offender had a foreign accent.
The van is white, and was dirty at the time of the incident.
PC Nazia Hussain said: “This was a frightening experience for the victim, who has been left shaken by the incident.
“I am determined to bring the perpetrator to justice, but I will need the public’s help.
“I would urge anyone who saw either vehicle yesterday evening travelling along the A421 or parked in the lay-by just beyond the Windmill Hill Roundabout and prior to the BP Garage, to contact police immediately. You may have vital information, no matter how insignificant you think it might be, that can aid our investigation.”
> Call police on 101.