Arsonists started a fire in a house by reaching through the letterbox.
The attack took place at about 12.45pm yesterday (Thursday, July 23) in Robin Lane, Wellingborough.
Police say the offenders reached through the letterbox of the house to set fire to a front-door curtain.
The fire was extinguished promptly and did not cause any injuries, but officers say the incident could have been a lot more serious.
One of the arsonists was black,slim, about 5ft 8in tall, in his late 30s to early 40s and with short-greying hair and a beard.
He wore a red T-shirt and a black body warmer.
The second man was white with a medium build, also about 5ft 8in and in his mid-30s.
He was bald with a tattoo from his neck leading down to his chest, and wore a blue T-shirt and a black body warmer.
The incident is not believed to be linked to an arson attack in Robin Lane earlier this month, one of seven which took place on the same night in Wellingborough.
Witnesses, or anyone who knows anything about this incident, should call Northamptonshire Police on 101.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.