A psychiatrist is gunned down in a drive-by from a Ferrari. Her killer is an accountant she has never met.
A realtor is bludgeoned to death while showing a house. His killer is a man he's never met.
A travel agent is shot to death in his agency. His killer is a man he has never met.
A bizarre string of murders is happening in Los Angeles, with the murderers seemingly having no connection and no motives to their victims.
"Murder X 4" displays symptoms of the following tropes:
- Body In A Bread Box: Tab Vaughn's corpse is found stuffed in a closet of the house he is showing.
- Boom, Headshot!: Nick Owen chooses this method of suicide when Steve's caught up to him for Celeste's murder.
- Bludgeoned to Death: Tab Vaughn was killed courtesy of a fire poker to the head.
- Freeze-Frame Bonus: Pausing when Mark discovers all the people that Montana Mutual Insurance covers shows their full names and their illnesses.
- Kill and Replace: One of the killers murders real estate agent Tab Vaughn at an open house. But as people arrive to look at the house, the killer is forced to wear Tab's jacket and act casual until he has an opportunity to escape. Unfortunately for him, he killed Vaughn the same day Mark and Steve decide to look around at the open house.
- Motor Mouth: Evelyn, the woman of the couple looking over the open house and stealing whatever's not nailed down, much to her partner's chagrin.Garth: Evelyn, we have the right to remain silent. Use it!
- Murder, Inc.: Rogin runs one of these out of Montana Mutual Insurance. He moves from hospital to hospital finding people who need someone eliminated. He then finds patients with terminal illnesses and solicits them to commit the murders in exchange for insurance benefits to be paid out to the killers' families once they die.
- No Honor Among Thieves: This is shown to be the motive for Maxwell's murder: he ran a smuggling business out of his travel agency, and his partner decided he'd rather not split the profits.
- The Sociopath: Rogin, without question. He effectively preys on people in a living hell to murder other people just for money, and when he's found out, tries to bargain for his freedom with a woman's life.Mark: So you're just fine sitting here letting it happen.
Rogin: It won't be on my conscience. I don't have one. - Tampering with Food and Drink: Celeste Kirkpatrick's killer Nick Owen first tried to kill her by slipping baneberry into her coffee. However, as she had eaten a lot of dairy due to an ice cream party held for a leaving employee, all that happened was her getting sick in a way she blamed on a stomach bug. This forced Nick to shoot her in a drive-by to get the job done.
- Terminally-Ill Criminal: Every killer in the episode (aside from Rogin himself) is facing a fatal illness, and killing their targets so that their families will see full benefits when they pass on.
