A man dressed as Batman walked into a West Yorkshire police station in the middle of the night and said "I've caught this one for you" as he handed over a wanted alleged criminal, officers have said.
Police said the mystery caped-crusader "then promptly vanished into the night to fight crime and the fear of crime in Bradford".
Officers say they do not know the identity of the man, who was dressed head-to-toe as the comic book hero when he walked into Trafalgar House police station with the 27-year-old wanted man.
The stocky, mystery man was posing as the camp 1960s incarnation of the famous DC Comics character, rather than the dark, black figure familiar to fans of the Tim Burton and Christopher Nolan film versions.
But he left the police station, which is just a short walk from the city centre, without leaving his name.
The man he handed over had been wanted by police in connection with a number of alleged offences. He was later charged with handling stolen goods and fraud-related offences, and will appear before magistrates on Friday.
The incident happened in the early hours of February 25.
A spokesman said: "The person who brought the wanted man into the station was dressed in a full Batman outfit. His identity, however, remains unknown."
The mystery was announced by the neighbourhood police team for the Buttershaw area of Bradford on their Facebook page.
The Facebook post promoted a rush of theories on the internet, including many who suspected the arrested man may possibly know the mysterious crime-fighter - especially as there appears to be little sign of any struggle.