Arsonists damaged both a house and a car in Higham Ferrers after setting fire to a bush.
The hedge outside a property in Linden Avenue was set on fire some time between 1.30am and 2am on Wednesday, April 15.
The fire quickly spread to both a Ford Fiesta which was parked nearby and the guttering of the property.
Officers investigating the case believe the fire may be linked to an incident which happened in nearby Oakes Drive at a similar time.
Witnesses should call Northamptonshire Police on 101 or Crimestoppers on 0800 555 111.