It's Always Sunny in Philadelphia Wiki

"Mac Is a Serial Killer" is the tenth episode of the third season of It's Always Sunny in Philadelphia.


After reading about a serial killer terrorizing young women, the Gang suspects that Mac may be the serial killer when they notice that he hasn't been to the bar much lately.


10:00AM on a Thursday

The gang is sitting around in the bar when Frank reads about a serial killer who has been killing young attractive blondes. Mac enters and everyone is suspicious of him when they accuse him of not coming home the night before and they notice scratches on his neck. Frank is sure that Mac is the serial killer. Frank declares that he is going to get the chainsaw. Dennis and Dee think that Mac isn't smart enough to be the serial killer.

Frank and Charlie follow Mac trying to figure out what he's been up to. It turns out that Mac has been visiting Carmen the trans woman. The two of them are dating, but no one knows yet. It turns out that the scratches on Mac's neck were from when Carmen and him were making out. Carmen flatters Mac and reassures him. Meanwhile, Frank and Charlie are playing with a chainsaw while staking out Mac. They then break into Mac's apartment and find a book on human anatomy. Mac has a chapter highlighted on the removal of human genitalia.

Meanwhile, Dennis and Dee try and catch the serial killer by luring him into killing. Dee dresses up as a prostitute to lure the serial killer out. Instead, she attracts the attention of Pepper Jack the pimp. Pepper Jack tries to pick up Dee and add her to his stable of hoes. Dennis tries to break the two up and Pepper Jack demands to be paid. So Dennis has to give up his Fraggle Rock thermos in order to buy back Dee.

Charlie confronts Mac and tells him that he knows where he's been. Of course, Charlie thinks that he is serial killing and Mac thinks that Charlie knows about himself and Carmen. Charlie decides to take on Mac as a client and begins doing lawyer stuff, such as humming the Law and Order theme song. Next, Charlie and Frank interview Mrs. Mac and try and pry loose some clues from her. They ask her "Do you think your son is out there killing people," and she answers yes.

Dennis and Dee then decide to stalk the Waitress to get into the mind of the serial killer. They go to a hardware store where Dee's neighbor Gary works. They decide to pick up some killing tools and take them for free so that there is no paper trail leading the tools back to them. Next they begin to stalk the Waitress. Dee is dressed like a psycho clown and Dennis is dressed like a painter. As they follow the waitress down the street Dee's shoes squeak loudly giving themselves away to the waitress who them sprays them with pepper spray. Dennis and Dee retreat into a bathroom to wash the pepper spray out of their eyes. Frank jumps out the bathroom stall because he has been spying on them. The three of them then hatch a plan to lure Mac into a compromising situation.

Mac and Carmen have an argument and Mac tells Charlie that, "She won't talk to me anymore." Charlie thinks that this is evidence of Mac being a crazy person. Dee, Dennis and Frank call Mac up and pose as "Sandy" a young woman who wants to hook up with Mac. The three of them then head to Gary's apartment to catch Mac in the act. Mac enters with some wine coolers and no condoms. Dennis, dressed in a suit, then confronts Mac about what he is doing there. Dee comes out with a video camera and Frank comes out with his chainsaw. Charlie enters and attempts to defend Mac based on an insanity plea. Mac is forced to admit that he is not the serial killer and has in fact been banging Carmen. Charlie decides to celebrate his legal victory with a beer and opens Gary's fridge to find a bunch of severed heads. They all realize that they are in the serial killer's apartment when Gary enters and Frank fires up his chainsaw and what happens to Gary is left to the imagination.



Guest Starring[]


  • Marcuis Harris as Pimp
  • Bill Chott as Gary


From an alternate take

  • This episode was available on MySpace from August 16, 2007 to August 23 - a month before the 3rd Season premiere, and more than two months before it was actually broadcast on FX.
  • During the scene in the Hardware store, in the background you can hear "Honey Bunch" by Karl Grell (from Soundtrack of the show).
  • The scene with Dennis and Dee stalking the Waitress at night was the last scene shot for Season Three in Philadelphia, PA.
  • In this episode, Charlie appears to be living out his fantasy of being a lawyer on the NBC series "Law & Order". Charlie Day and Rob McElhenney have both played minor characters in the series.
  • The final scene where The Gang confronts Mac is a parody of NBC's show "To Catch A Predator".
  • Dennis' line to Dee "You're like a female Larry Bird" later transforms into the series' running joke about how Dee looks like a "GIANT BIRD". [the joke originated with Mac calling her a "Big Bird" in "The Gang Gives Back".
  • All of Frank's questions about Mac are accurate, Mac was shown to be an angry and volatile child in "A Very Sunny Christmas," he said he hates women in "Mac And Charlie Write A Movie," and he was raised in an dysfunctional home.
  • Mac goes to "Sandy's" apartment despite not being told where it is.
  • At the beginning of the episode Frank says that the serial killer is targeting blondes. None of the heads in the serial killer's freezer are blonde.
  • Dennis is clearly a little too excited about the prospects of murdering the Waitress having forgotten that the plan was just to get into the mind of the serial killer, (i.e. Dennis is a psychopath).
  • When Charlie tells Mac to "let the serial killer" out, this is a reference to the film Primal Fear. He even paraphrases the prosecuting attorney, who also said she wanted to wash her hands.


Mini-Frank Reynolds.jpg   I'm going to go oil my chainsaw.
What?   Mini-Dee Reynolds.jpg
Mini-Dennis Reynolds.jpg   Frank, we don't need the chainsaw. Is that what's in that bag?
Oh, we do...because drawing a confession out of someone is like doing a beautiful dance...a beautiful dance with a chainsaw.   Mini-Frank Reynolds.jpg
Mini-Dennis Reynolds.jpg   He makes less and less sense as the days go by.
I don't get all.   Mini-Dee Reynolds.jpg

Mini-Charlie Kelly.jpg   Look, Mac, I'm tired and I want to go home, I just want to wash my hands of this whole stinkin' mess, so I'm gonna ask you just one time: did you, or did you not, snap into an alternate personality and go on a serial killing rampage?
What? No!   Mini-Mac.jpg
Mini-Charlie Kelly.jpg   Wha... yes you did. You're two people, right? Let's see the other one. Let him out.
Let who out?   Mini-Mac.jpg
Mini-Charlie Kelly.jpg   The serial killer! Let the serial killer out!
I'm not a serial killer!   Mini-Mac.jpg
Mini-Frank Reynolds.jpg   Then why all the shady behavior?
I've been banging the tranny! I didn't want you guys to find out!   Mini-Mac.jpg
Mini-Charlie Kelly.jpg   No, you've been... what?!



From deleted scene:

Mini-Charlie Kelly.jpg   I think I could be a really good lawyer...
Don't you think you should know how to read or write?   Mini-Dee Reynolds.jpg
Mini-Charlie Kelly.jpg   Objection, hearsay!
Season 3 Episodes
  1. "The Gang Finds a Dumpster Baby"
2. "The Gang Gets Invincible"
3. "Dennis and Dee's Mom Is Dead"
4. "The Gang Gets Held Hostage"
5. "The Aluminum Monster vs. Fatty Magoo"
6. "The Gang Solves the North Korea Situation"
7. "The Gang Sells Out"
8. "Frank Sets Sweet Dee on Fire"
 9. "Sweet Dee's Dating a Retarded Person"
10. "Mac Is a Serial Killer"
11. "Dennis Looks Like a Registered Sex Offender"
12. "The Gang Gets Whacked (Part 1)"
13. "The Gang Gets Whacked (Part 2)"
14. "Bums: Making a Mess All Over the City"
15. "The Gang Dances Their Asses Off"