Midsomer Murders Victoria Bartlett Tries to Kill Jonah Bloxham a Worm in the Bud

At Jonah's house, someone comes in and hits him over the head with a wrench. He falls to the floor. All the photos are removed and the place is set on fire.
Jonah is rescued and the fireman says that he took in a lot of smoke and he's got a nasty crack on his head.