Firefighters were called to a garage blaze in the early hours of Christmas morning.
Crews from Tring, Berkhamsted and Hemel Hempstead went to the fire at Church Lane, Hastoe, near Tring, just after midnight.
When they arrived the detached garage was well alight. Firefighters used two hose reels and breathing apparatus to extinguish the blaze.
The fire was out just before 1am and crews spent around 20 minutes dampening down the area.
Police are treating the fire as suspicious and are currently investigating.
Anyone with information is asked to contact Det Con Geoff Smith on 01442 271056, quoting reference URN 15 of 25/12/12.