An armed robber allegedly tried to demand cash, but left empty handed, after an incident at a shop in Heckington.
The incident happened at the Premier shop on Church Street in the Lincolnshire village at around 4pm on October 30.
A person entered the store with a weapon, believed to be a hammer, and asked for cash. The shopkeeper refused and the person left the store.
Police said the person was wearing black clothing, a face covering and brown boots. They may also have been wearing a pair of aviator sunglasses at the time, police added.
Lincolnshire Police launched an appeal for witnesses on Wednesday, November 10.
Anyone with information, or who was in the area at the time and may be able to assist with the investigation, should contact Lincolnshire Police on 101 quoting incident 204 of October 31.