A man was taken to hospital with serious head injuries following a party at a house in Midlothian.
The 28-year-old was found in the garden of a property in Braeside Road North, Gorebridge, at around 4am on Saturday.
Police said he appeared to have been attacked, but the full circumstances of the incident were unclear.
The man was taken to hospital where he was in a serious condition.
A spokesman for Lothian and Borders Police said: "At this time we are trying to determine exactly what happened to the male and it is vital that anyone who saw or heard any disturbance comes forward.
"It is believed a party was ongoing within the house where the male was assaulted and police are keen to speak to those who were in attendance at this party.
"Similarly, anyone else with information regarding this incident is asked to get in touch immediately."