A man walked into a Lincoln betting shop armed with a knife before stealing money and leaving the premises.
The incident happened at around 6.30pm on Saturday, August 4 at Coral bookmakers on Lincoln High Street when the man entered the shop and demanded money from the cashier.
The money was then handed over to the man, who left and rode off on a bike towards the city centre.
Nobody was physically hurt during the incident, but people inside the shop at the time were left shaken and upset, police said.
Lincolnshire Police would like to trace the man caught on CCTV to see if he has any information to help with their enquiry.
Anyone with information or who recognises the man should contact police on 101 or via email at [email protected] quoting incident number 374 of August 4.
It can also be reported through the independent charity Crimestoppers anonymously on 0800 555 111 or online here.