A victim was injured after being attacked at home by intruders who made off with cash.
Police want help tracing the offenders, who broke into the house in Irchester Road, Rushden, at about 10pm on Tuesday, August 28.
Officers say a substantial amount of cash was taken.
A white van was seen parked outside around the same time, and police would like to speak to anybody who may have seen the van or any other suspicious activity at the time.
The victim was treated at Kettering General Hospital for a minor head injury.
Witnesses, or anyone with information, are asked to contact Northamptonshire Police on 101. Alternatively, information can be given anonymously to Crimestoppers on 0800 555 111.