Police are hunting for a man who indecently exposed himself to another man in the Grosvenor Centre toilets.
The offender carried out a lewd act, while exposing himself to the victim, around 5.10pm on Wednesday, December 30.
The offender is described as white, in his early 20s, around 5ft 8ins tall, with a tall, slim or scrawny build with blonde-like hair that was short on the sides and slightly longer and messy on top.
He was also wearing a hearing aid.
Anyone with any information can call Northamptonshire Police on 101. Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.