Police appealed for witnesses to the attack on Sunday night
An object was set alight and pushed through a letterbox in what police have described as an arson attack in north Belfast.
It happened at a flat in Castletown Avenue about 21:00 GMT on Sunday.
A man inside the house was not injured, but was left badly shaken.
The fire was extinguished by firefighters.
Police have appealed for information.
Det Insp Michelle Griffin said: "Police are investigating this as arson with intent to endanger life and this could have ended in a tragedy."
