Mark's friend, lawyer Bill Stratton, is shot dead in his office on the night of his one year anniversary to his newest wife, Jennifer. Suspects seem to pile up, but the evidence soon starts leaning towards Jennifer. Things are further complicated when Jennifer reveals her sister to Mark and Steve... her twin sister.
"Murder Murder" displays symptoms of the following tropes:
- The Alibi: Each of the main suspects in Bill's murder, and then Jennifer's, turn out to not have been able to kill her, thus clearing them of Bill's murder:
- Alan Helms was in the drunk tank when Jennifer was killed, Lenore was in her closing bookshop with the movers, and Stan Macky was in Rome when Jennifer died.
- Bluffing the Murderer: Mark tells Jennifer she screwed up in particular because she put the contact lenses in Joan's eyes backwards. After she confesses and gets in Steve's car, Mark informs Steve she made no such mistake.
- Cool Car: Bill gives Jennifer a Dodge Viper for an anniversary gift.
- Deceased Fall-Guy Gambit: An interesting one. Jennifer fakes her own death by suicide, using Joan's body as hers.
- Did Not Die That Way: It is believed Jennifer killed herself by suffocating herself with the carbon monoxide fumes from her car. Mark soon figures Jennifer's skin was too pale to have succumbed to carbon monoxide poisoning and the garage was too big for her to have died at the time she did. Examining the body with Amanda reveals she was actually strangled to death.
- Graceful Loser: After Jennifer is told by Mark how she messed up, she takes the fact that anyone can mess up in stride, and leaves with Steve with no fuss.
- Impostor Forgot One Detail: As "Joan" is packing to leave Los Angeles, Mark notices her put a bottle of saline solution into her bag. He later realizes this as proof "Joan" is actually Jennifer, because while Joan wore glasses, Jennifer wore contact lenses, and it wouldn't make sense for Joan to pack saline solution if she didn't wear contacts.
- Kill and Replace: Jennifer murders Joan and makes it look like Jennifer committed suicide in order to take her place.
- Murderer P.O.V.: Bill Stratton is depicted dying in this way. He comes around the corner into his office and demands to know how his soon-to-be killer got past security. The killer shoots him promptly through the chest.
- Sibling Murder: Jennifer murders her twin sister, Joan.
- Skewed Priorities: Jesse is initially more fascinated about Jennifer and Joan being twins than the investigation itself, and spends time telling Mark and Amanda some facts about twins. Both doctors couldn't care less.
- Special Guest: Robert Vaughn as Bill Stratton.
- Twin Theme Naming: Jennifer and Joan.
- Who Murdered the Asshole: Every suspect for Bill's murder has their own grievances towards the guy.
- Wrench Wench: Jennifer Stratton is quite skilled with auto mechanics.
