Some surgeons do their stitches in a criss-cross pattern...
Mark finds himself outraged at Marsha McArthur, a woman sent into Community General to make severe budget cuts. She has let him know in certainty that if he won't roll over for her cuts, she will either give him "early" retirement or let his contract expire. He says that he'll gladly take her down with him if he's forced out.
That promise comes eerily close when McArthur is found dead in a park after having called Mark to meet her there. This was done by a mysterious man doing Mark a little "favor". Unfortunately, he wants Mark to do him a "favor" in return...
"The Murder Trade" displays symptoms of the following tropes:
- Alliterative Name: Marsha McArthur.
- Asshole Victim: Marsha was planning on making drastic budget cuts that would have hurt the patients of Community General and was willing to can Mark if he wouldn't sign off. She didn't deserve to be used as a pawn in Simon's little scheme, but she sure as Hell wasn't a nice person.
- Crazy-Prepared: Steve sets up a tracer to find Mark's stalker when he calls for instructions. The caller directs Mark to a payphone for his instructions on his "test", meaning Steve can't get a trace in.
- Disposable Sex Worker: Simon's test to see if Mark has the guts to pull off his murder is instructing him to kill a prostitute he drugged and left in a motel room.
- Frame-Up: Simon Trent plans to let Mark take the fall for the murder of McArthur if he doesn't fulfill his side of the "bargain".
- Greater-Scope Villain: The creditor representing the loan sharks that Dr. Trent owes money to. While Steve and the Community General staff learn of him having met up with Dr. Trent, they only catch the latter at the end once he attempts to murder his cousin and then Mark.
- Inheritance Murder: Dr. Trent is trying to kill off his cousin, as she named him the beneficiary of her life insurance policy after her husband passed away, and he really needed to pay off his debts to loan sharks.
- Make It Look Like an Accident: Mark deduces that his psycho chose him because a doctor would best know how to make a death look like natural causes.
- Psycho Psychologist: Dr. Trent is a psychiatrist, and perfectly willing to kill a total stranger and coerce another stranger into committing murder for him to save his own hide.
- The Spook: Dr. Trent goes out of his way to make sure that no one can suspect him, mainly by not revealing his name to Mark, and using a payphone to contact Mark so that Steve can't trace him. This effectively makes it difficult to prove that he even exists to the police, let alone the fact that he committed the murder of McArthur.
- "Strangers on a Train"-Plot Murder: A deranged psychiatrist kills a hospital administrator who was going to recommend that Dr. Sloan be dismissed from Community General when he protested her bone-deep budget cut recommendations. The psychiatrist then calls up Mark and told him, "Now you owe me a favor." Mark, of course, refuses to play along.
- You Have Outlived Your Usefulness: When Mark finally manages to catch Dr. Trent in the act of murdering his cousin and foils his assassination attempt, the latter tries to kill the former before making a run for it.
