Detectives are appealing for a taxi driver and couple who are key witnesses to a roadside assault.
The victim was a 33-year-old woman from the Maldon area.
She had been driving her silver Ford Focus on Steeple Road, Latchingdon at 3am on Sunday when a male motorcyclist forced her to stop.
An altercation between the man and woman followed, during which the woman was punched in the face.
Investigating Officer, Dc Carley Parodi, said: "This woman was forced to remain inside her car for a couple of hours while this man, whom she knows, assaulted her.
"During this time, a dark grey Hackney-style cab stopped and it's driver and the two other occupants spoke to her in order to ensure she was safe and well.
"She was unable to speak freely so they had no option other than to leave.
"We now want to identify these three and speak to them as they are clearly key witnesses to this assault."
The woman later got out of the car and returned home while the man rode off on his motorcycle.
She suffered minor facial injuries and did not need medical treatment.
Anyone with information in connection with this domestic assault is urged to contact detectives at Chelmsford police station on 101 or Crimestoppers on 0800 555111.