The masked robber entered the Subway on Wokingham Road as staff were cashing up at 11pm on Thursday.
The offender, wearing black with his hood raised and a scarf over his face, threatened staff with a weapon in a plastic bag.
He then lent across the counter and demanded money but was refused by staff.
He fled the scene empty handed, running towards Cemetery Junction.
Det Con Natalie Davison said: “I am appealing for anyone with information to come forward as soon as possible. The member of staff was uninjured although naturally left shaken.” Those with information should contact DC Davison via the Thames Valley Police Enquiry Centre on 101.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article