Two women have been threatened by a man who got into the back of their car at night and demanded money.
The women, aged 26 and 31, had just finished their shift at Scotmid Store in Riddell Street, Clydebank, at about 22:00 on Christmas Eve when the incident happened.
They got into a blue Ford Focus which was parked in front of the premises.
But before they drove off, a man dressed in dark clothes got into the back of the car.
He threatened them and demanded money and other personal belongings but ran off after they refused his demands.
Det Sgt Stuart Gillies, from Clydebank CID, said: "Thankfully the women were not harmed during the incident and officers are currently examining CCTV and conducting door-to-door inquiries in order to trace the suspect.
"We believe he may have been lurking around outside the store prior to the incident taking place and I would appeal to anyone who noticed a man acting suspiciously to please get in touch."