Three cars were set ablaze after fire spread following an arson attack.
Detectives investigating the attack for Hertfordshire Police are appealing for any witnesses to the incident to come forward.
The arsonist struck in Long John, in Bennets End, between 11.30pm and 11.40pm last Thursday (April 20).
A vehicle parked on a driveway along the road was set alight, with the fire then spreading to another vehicle parked on the driveway.
It continued to spread to a further car parked outside the neighbour’s property.
The front door of the first house was also damaged during the fire.
Detective Sergeant Paul Perkins, from the Dacorum Local Crime Unit, said: “Thankfully no one was injured during the incident but these reckless actions could have had very serious, or even fatal, consequences.
“I am appealing for anyone with information about what happened to please come forward.
“It is believed that a person may have been riding a motorbike along the road at the time and I am keen to trace this person as they may have seen someone acting suspiciously or have other information which could assist our enquiries.”
Anyone with information is asked to contact the Dacorum Local Crime Unit via the non-emergency number 101, quoting crime reference D1/17/3227.
Alternatively, if you have any information about this incident, you can contact the independent crime-fighting charity Crimestoppers anonymously on 0800 555 111.
No personal details are taken, information cannot be traced or recorded and you won’t need to go to court.