Police Concern Over Shropshire Road Incident
Their car - thought to be a black VW Golf or Audi A3 - had pulled up with both occupants stood outside and the young woman upset and crying.
One passer-by was so concerned he stopped to see what was happening. The man then grabbed the woman and they both got back into their vehicle and drove off.
Police are now trying to establish the circumstances and treating the matter as a suspicious incident.
They are urging the man and woman to make contact to provide reassurance that nothing untoward happened.
An appeal has also been issued for the two women occupants of a Landrover Discovery which also stopped to help, to get in touch as vital witnesses.
The incident happened on Sunday night at around 7pm or 7.30pm. The man and woman involved are thought to be Asian and the woman, who was aged in her late teens or early twenties, was wearing a blue sari.
A West Mercia police spokesperson said: "There may be a perfectly innocent explanation but we are anxious to establish the well-being of those involved.
"Anyone with information should call 0300 333 3000 or contact the anonymous Crimestoppers charity on 0800 555 111.