A 27-year-old man was the victim of an attempted robbery in Central Milton Keynes on December 12.
Police are appealing for witnesses to the incident which occurred in the underpass in Midsummer Place, between the John Lewis car park and Milton Keynes Theatre, at about 8.15pm.
The victim was walking in the underpass when he was approached by a man, who said something either in another language or with a foreign accent.
The offender then lunged at the victim, who was pushed to the floor.
An altercation occurred, during which the offender brandished a knife.
If you have any information contact PC Graeme Poulton via the Thames Valley Police Enquiry Centre on 101.