A Good Samaritan was viciously beaten after he intervened in an argument at a Preston takeaway.
The victim was attacked in Giacomo's Pizza Spaghetti House, Hill Street, as he asked a man and woman to stop rowing.
A third man, believed to be in his 40s, attacked the victim, hitting him on the head and knocking him out.
Det Insp Jonathan Holmes, of Preston CID said: "This was an appalling attack on someone who did nothing more than try to calm down a heated argument."
The attacker then fled the shop, along with the arguing couple, immediately after the attack at 1.45am on Sunday.
The victim, a 44-year-old man who was in the premises on his own, was taken to the Royal Preston Hospital suffering cuts and bruises to his head. He was kept in overnight for observation and discharged Sunday afternoon.
Police are now gathering footage from CCTV cameras in the area and speaking to witnesses in a bid to track down the attacker.
The wanted man is described as white, in his early 40s, with a shaved head and stocky build.
They also want to speak to the man and woman involved in the argument.
The woman is described as in her 20s, with a slim build. Her companion was white, with short hair.
Det Insp Holmes added: "He acted out of concern for the woman and I would urge anyone with any knowledge of the incident to come forward."
Anyone with information is asked to call Preston CID on 01772 203203.
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