Mr. RK and I don't watch TV, but we are addicted to several BBC series (Dr. Who, Agatha Christie, etc.) - and murder mysteries are right up there. But I can't help thinking there are some common themes, regardless of who is writing, starring or producing. We recently got hooked on a show called Midsomer Murders. By the look of it, someone in that fictional county gets whacked every week. This show is no exception to the rules, which I have outlined below.
1. Everyone who has household staff of any kind - an assistant, a cleaner, a cook, etc. - is going to get killed, probably violently. It's these poor schmucks that always, ALWAYS end up finding the bodies.
2. Every detective genius has a not-so-bright sidekick, who nevertheless ends up unexpectedly shedding light or saying something out of the blue that stimulates the detective's little gray cells and ends up - voila! - helping him solve the case.
3. Drink something caffeinated before you watch this stuff. With few exceptions, there will always be lots of "arranging matches," as Eddie Izzard puts it, before you get anywhere near the plot.
4. Invariably, if the detective is a man, he'll be a foodie, and have some kind of OCD.
5. Inevitably, some kind of secret or illicit sex relationship will be revealed. Usually it has nothing to do with who killed whom, but it helps break up the arranging of matches a bit.
6. If there is a pet involved, it will usually be more helpful to the detective, in terms of solving the murder, than the humans.
7. If the murderer used poison, s/he will be stupid enough to offer a drink or food to the detective, who will be smart enough not to drink it (even if it appears that s/he does.)
8. The motive is almost always greed, sex, or revenge, coupled with a person who has totally gone around the bend. I'd really like to see it be over something like, say, food, or a parking spot, or bad fashion choices. Like Mrs. Jones is afraid that Mrs. Smith is going to win the cupcake baking contest, so she puts arsenic in the frosting. Wendy is sick of Larry wearing ball-busting pants to work and taking her parking spot, so she pushes him down the elevator shaft and makes it look like an accident. Something interesting like that.
9. Once the detective finds out who the murder is, s/he will never just say, "Hey! You're busted. Down to the station with you." S/he will lay out a long-winded speech telling the killer exactly why s/he did it.
10. The killer won't, as you'd think, start to run away during the speech. Rather, s/he always A. denies it and B. then admits it with a gleam in their eye.
There's your guide. Happy watching!