A taxi driver was threatened as he waited for a customer by a man armed with a weapon who demanded money through the open window.
The driver managed to get away without anything being taken in the attempted robbery which took place in Montrose Street, Corby, at about 10.30pm on Saturday, June 13.
The offender is described as black, aged about 30, 5ft 8in with a slim build.
He wore a dark coloured hoody.
Witnesses, or anyone who knows anything about this incident, can call Northamptonshire Police on 101 or Crimestoppers anonymously on 0800 555111 or use the anonymous online form at www.crimestoppers-uk.org.