A man was marched to a cashpoint in Kettering after robbers threatened to stab him.
The terrifying incident took place between 10.30pm and 10.45pm on August 12 in an alleyway near Albert Street.
Two men approached the 23-year-old victim, who was walking alone through the alleyway.
One of the men stood directly in front of him with a knife handle visible in his waistband and threatened to stab the man if he did not hand over money.
They then escorted the man to Tesco in Windmill Avenue and tried to get him to withdraw money from his account.
A police spokesman said: "This was unsuccessful and the man was then pushed to the ground before the offenders fled."
The spokesman added that one of the robbers was a white man and the other was a black man.
Witnesses or anyone with information should contact police on 101 or Crimestoppers anonymously on 0800 555111.