Here are two rules about killers that you might not know if it weren’t for television. 

• If there is a deranged killer on the loose this will also coincide with a thunderstorm that has brought down all the power and phone lines in the vicinity.

• If a killer is lurking in your house, it’s easy to find him. Just relax and run a bath – even if it’s the middle of the afternoon – then look in your bathroom mirror and he will suddenly appear behind you.