Detectives are carrying out house-to-house inquires after a man was found unconscious in a Devon car park with a serious head injury, police have said.
Officers appealed for witnesses after they were called at 04:00 BST to Russell Street Car Park in Tavistock.
A 45-year-old man was in a critical condition at Derriford Hospital in Plymouth, Devon and Cornwall Police said.
Det Insp Emma Lefort said officers were appealing for anyone who saw or heard a disturbance or anything suspicious in the area between 02:00 and 04:30.
Det Insp Lefort said there would be an increased police presence in the area, while officers remained at the car park and carried out house-to-house inquiries.
She appealed for anyone with CCTV footage or dashcam footage to get in touch with police.
