Two motorbikes approached a car from behind before one rider walked towards the car and pulled out a machete.
The incident happened between 6.30pm and 7.15pm on Tuesday, August 29 when the motorist was driving along Tonmead Road in his car, Northamptonshire Police today revealed.
Two motorbikes approached the car from behind, one of which rode off but the other pulled wheelies close to the car before pulling in front of it. The rider got off the bike and walked towards the car.
When he got to the window, he threatened the driver with a machete. The man in the car drove off towards the A43 towards the Round Spinney roundabout and the rider got back on the bike, followed, parked in the layby on the island near Talavera Way and threw stones at the car.
A Northamptonshire Police spokeswoman said: "The offender is described as black, 5ft 8in with a skinny build, a black moustache and wearing a denim jacket, jeans, and trainers. He was riding a red and white trials bike with no number plates."
Anyone with information can contact Northamptonshire Police on 101. Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.