An 18-year-old female is in hospital with serious injuries after a single vehicle crash.
The incident occurred on an unnamed road in Smilog Woods, near Talbot Green, Llantrisant at around 1am on Monday, October 5.
It involved a blue Ford Fiesta which was travelling towards the A4119 at the time of the crash.
The teenager, who was a passenger in the car, is being treated for serious injuries at the University Hospital of Wales in Cardiff.
A 29-year-old man was also treated for injuries but has been released from hospital.
Officers from South Wales Police are appealing for any witnesses or anyone with dashcam footage to come forward.
A spokesman for the force said: "Officers from our roads policing unit are investigating a single-vehicle collision which occurred on an unnamed road in Smilog Woods, near Talbot Green, at around 1am on Monday, October 5.
"The collision involved a blue Ford Fiesta which was travelling towards the A4119.
"An 18-year-old girl, who was a passenger in the vehicle, sustained serious injuries for which she continues to be treated at the University Hospital of Wales.
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"A 29-year-old man was also treated or injuries but has subsequently been released from hospital.
"We are continuing to investigate the circumstances of the collision and are appealing for any witnesses or anyone who saw the car prior to the collision, to come forward.
"The car is believed to have been in or near Talbot Green Retail Park prior to the incident."
Anyone with any information that could help police is urged to contact 101, quoting occurrence 2000362858.
