Police find a dead man in a meth lab in Seattle Washington. It's the second murder perpetrated by the same unsub. The first man was murdered in Albany, NY.
In each case, the victim's face was painted white and black, and both died of a cardiac arrest.
Meanwhile, the team is down two people: Kate and now JJ as well, who has just given birth to her second child. Hotch is interviewing a replacement. He begins to interview Agent Tara Lewis but asks her to wait while he takes a phone call.
A woman walks down the stairs to her basement, shouting "hello". She gives the masked unsub a file then runs back upstairs in fear.
Morgan discusses the autopsy of one of the victims with the medical examiner who tells him that he was injected with a nutritional supplement one would normally drink. She confirms that the injection would cause a massive embolism, causing the victim great agony, and that it would have taken him up to an hour to die.
Morgan realizes narrows down the possible purchases of such supplements: senior citizens, anyone having trouble nutritionally or people unable to eat solid foods.
The team figures out that the unsub has a feeding port in his stomach because he's unable to eat or speak. They figure out the unsub is a hit man. And he leaves his victim with their faces painted as a message to his customers.
The unsub kills his third victim - Brian Taylor - and then paints his face.
The team discovers that Taylor had hired the unsub via the Silk Road to kill his father because of alleged abuse. They now realize the contract killer is doubling back to kill his former clients.
The unsub approaches a new victim, Al Eisenmund, a mechanic working in his garage.
Meanwhile, Garcia and Derek use a process of elimination to determine that Eisenmund is the unsub's next target.
Just as he's about to kill Eisenmund, the unsub gets a text. Instead of injecting him with the nutritional supplement, the unsub glues a live grenade to his victim's hands.
Reid comes up with a way to dissolve the glue, then they throw the bomb and it goes off.
Morgan questions Eisenmund about the fact that he contracted to have his fiancé killed. He says that after the hit, he started getting weird Facetime calls, and his webcam turned on for no reason. Scared for his life he reached out to another hitman to kill the first one. Only the hit went sour and the unsub instead got a bad gunshot wound to the face.
Morgan realizes that the unsub, not knowing who set him up, is now going around and killing all of his clients.
The team figures that the reason the unsub didn't inject his latest victim was because he realized his time was short; and that there was a mole in the police department who warned him via text that police were on their way. He had no time to wait for the embolism to work so he used another method - the grenade.
They check the license plates at the last victim's place, and realize that Captain Wilson of the local police force and his wife Betty have been working with the unsub, likely under duress.
The BAU and police raid the Wilson's house. Betty confesses to hiring the killer. She tells Rossi that she got hooked on drugs, and then hired the unsub to kill her dealer because he wouldn't leave her alone.
Meanwhile the unsub has Phill driving him to a location where he can kill him. Hotch confirms that Phil entered the destination location in the map application on his phone. Hotch tells him that they'll meet him at the location.
Suspecting a trap, the unsub picks up Phil's phone and dials home and puts the phone on speaker. Hotch gets Agent Tara Lewis to pretend to be Betty Wilson and, under Hotch's direction, instructs Phil -- in a loving way -- to "keep your head down". This instruction is given because the police sniper can't see the unsub. Phil moves out of the way and the unsub tries to escape.
Morgan chases him and manages to shoot him, but the unsub keeps running. Morgan and the unsub struggle. Morgan overpowers him and places him under arrest.
Hotch hires Lewis.
Morgan visits the unsub in the hospital. The unsub warns him that he's going to kill "The Dirty Dozen" next. He proceeds to rip the stitches from his face, and the nurse comes in, believing that Morgan has caused the injury. The unsub looks at Morgan and grins.