A woman was pulled into a car by a man and driven to a lay-by near Daventry where she was punched in the face and knocked unconscious.
The victim, who is in her 20s, had walked through the town centre from Tesco, down High Street and through the underpass at the bottom of Brook Street.
As she walked through the car park adjacent to Brook Street, she was pulled into a dark-coloured vehicle by a man and driven to a lay-by on the A45 London Road, near the entrance of Daventry MX Track.
The man then pulled her out of the car and punched her several times, causing her to fall unconscious.
When she came round she was able to escape and ran to a nearby garage to call for help.
The assault took place between 10.15pm on Saturday (November 3) and 2am on Sunday (November 4).
Detective Inspector James Larkin said: "This type of incident is very rare but also very concerning.
"Thankfully, the woman did not sustain any serious injuries, however, it was extremely distressing for her and she required hospital treatment for injuries to her face.
"An investigation is underway and we are appealing for witnesses.
"Anyone who may have seen the man or the vehicle during the times stated, or noticed anything suspicious either in the car park area near Brook Street or the lay-by on the A45, is urged to get in touch with police."
The car involved was dark in colour with black or grey leather seats.
The suspect is described as mixed race, about 5ft 4in, with a slim build and short, black curly hair.
He was wearing a dark-coloured hooded top and dark-coloured tracksuit bottoms with two white stripes down the side - the trouser legs were elasticated and zipped at the bottom.
Witnesses, or anyone with information, should call contact Northamptonshire Police on 101 or they can contact Crimestoppers anonymously on 0800 555111.
DI Larkin added: "We want everyone to be able to have a safe and enjoyable night out and we’ll have additional patrols in the area over the next few days.
"If you’re going for a night out, whenever possible, plan in advance how you’re going to get home, ideally by arranging a lift or pre-booking a taxi.
"If you choose to walk, stay with friends and try to pick a busy, well-lit route, avoiding quiet areas.
"Stay vigilant, carry a mobile phone with you and tell someone when you expect to be home."
Northamptonshire Police have published their tips on how to help keep you safe on a night out:
If you’re having a night out, plan how you’re getting home before you go
Taking a taxi? Ideally, book it in advance or take it from the taxi rank
Always keep the number of a reliable firm with you and know where the taxi ranks are
Avoid minicabs or private-hire cars that tout for business – they should always be pre-booked
When the taxi arrives, check it’s the one you booked. If in doubt, don’t get in
Stick with your friends and choose a meeting point where you’ll wait for each other if you get separated
Never accept a lift from a stranger – there are plenty of licensed taxis in our towns
Be aware of what you are drinking – if someone offers to buy you a drink, go with them to the bar and watch the drink being poured
If you notice someone who appears vulnerable, tell someone such as a door supervisor, street pastor or police officer, or call police on 101 or 999 in an emergency
Stay together and travel together. Don’t go off on your own and keep an eye out for your friends
It may sound obvious, but avoid walking through unlit areas, such as alleyways or churchyards
Keep a charged mobile phone with you and if you get separated, use it to call one another. If you feel at risk, call 999.