Sins of Commission is the fourth episode of the seventh series of Midsomer Murders and first aired 18th January 2004.
During the 12th Annual Midsomer St. Michael Literary Festival, local author Richard Rackham is found dead at the bottom of the stairs in his house. The pathologist confirms that his neck was broken before he fell and it is apparent that his computer is missing. When the book editor Neville Williams is also killed, Barnaby and Scott learn that he and Rackham were lovers. As the body count keeps rising, the police find multiple motives and several possible killers. Several characters were involved in affairs and some were involved in lucrative financial scams. The solution to the crimes is found when Barnaby unearths an author who has been writing under a pseudonym but who was about to let their true identity be known.
This episode includes examples of the following tropes:
- Behind the Black: Barnaby manages to pull this off: in one scene several characters have an argument, with it only being shown after they've left that Barnaby was sat in a chair in the same room the whole time. The thing is, he should have been plainly visible to them since his head clearly pokes up above the chair's back
- Bullying a Dragon: The co-conspirators figure it'll be easy to kill nice old Camilla. They are very, very wrong.
- Bury Your Gays: Averted, the first two victims are male lovers, but their deaths are followed by the death of a straight woman.
- Camera Sniper: A few suspects are seen through a camera lens like this. It turns out a housekeeper is photographing people for several reasons.
- Dirty Old Man: Tim is an old hippy and the village swim coach, he openly ogles the teenage girls who are at the community pool.
- Frying Pan of Doom: An intruder in the hall is knocked out by the housekeeper wielding a frying pan.
- Killing in Self-Defense: Three of the murders are a type of self-defence.
- Retired Badass: It turns out the three "victims" all tried to murder the same nice older lady - who happened to have been an agent with the Special Operations Executive during WWII.
- Straight Gay: Mystery writer Harry Poulson is a butch ex-policeman (and friend of Barnaby). He has had affairs with two men, but not a lot of people realise he's gay.
- Tap on the Head: One hit with a skillet to the back of the head knocks out David, but he's fine with no damage one scene later.
