A man in his 40s wearing a bomber jacket threatened a Wellingborough newsagents worker with a knife during a robbery.
At about 12.30pm last Thursday (April 11), the robber entered the shop in Park Crescent, walked around until two other customers left and then approached the counter.
He then produced a knife and threatened a member of staff.
Another man then entered the shop and the suspect put the knife up his sleeve and left.
A Northamptonshire Police spokeswoman said: "The suspect is described as white, about 5ft 9in, and in his mid to late 40s.
"He was wearing a black bomber ‘Everlast’ jacket, dark jeans, a black beanie style hat with grey hair sticking out of the back, and black gloves with white fingertips."
Anyone who was in the shop or nearby area around the time stated and may have seen the suspect or has information about the incident is asked to contact Northamptonshire Police on 101.
Information can also be provided anonymously to Crimestoppers on 0800 555111.