After a police department softball game, the whole gang goes to a bar to celebrate McNab's birthday. But, as the waiters bring out the cake, Shawn spots a hooded man by the register with a bulge in his jacket. He runs to warn Lassiter who pulls out his weapons just as the hooded man starts to fire. After a barrage of bullets, the man manages to escape. The cops think it was an attempted robbery but Shawn says the man came there specifically to kill one of them. He believes he will try again, but if they can figure out which one of them was the target, it will give them a clue to the man's identity. The crime scene unit finds a piece of the man's hooded sweatshirt and a motel key in the alley behind the bar. It looks like his pocket ripped as he was fleeing the scene. Lassiter and Juliet head to the motel while Shawn and Gus go back to the bar. While there, Shawn remembers the shooter was wearing an expensive watch, which proves he wasn't a junkie thief. Shawn also realizes that he was deliberately standing in the blind spot of the security cameras. The shooter is much smarter than they give him credit for, which means that the key was planted to lure the cops to the motel. Not only that, but after Shawn recreates the shooting he realizes the target is Lassiter. Shawn calls to warn Lassiter, who is on his way back from finding nothing at the motel. As he leans down to pick up the phone from the floorboard of his car, a shot comes through his windshield, narrowly missing him.
Back at the police station, Lassiter is unharmed but infuriated. He wants to put away whoever did tried to kill him, but Chief Vick takes him off the case and puts him on 24 hour watch at the police station. Shawn, Gus and Juliet decide that whoever's trying to target Lassiter is most likely someone he put in jail, and they narrow it down to a local drug lord named Ivan Petrovich. Lassiter realizes that McNab was with him when he arrested Petrovich, so he may be in danger too. Juliet goes to check on McNab, to see that he's safe. He too is to be put under 24 hour watch. McNab agrees, but just wants to get his mail first, but when he opens his mailbox it explodes, sending him flying. Chief Vick is worried that everyone involved with the case is in danger, including Shawn and Gus, who were listed as consultants despite not doing anything except taking a phone call. Gus runs to the Psych office where he finds Shawn running on an elliptical, with a note saying, "If your heart rate drops under 150 you DIE". Gus calls the police, but it turns out the note was just written by Juliet, who was trying to motivate him, and the beeping sound was just their phone.
Lassiter insists on being part of the team that takes down Petrovich, and Shawn has a vision about an old drug front that Petrovich used to use. Shawn, Gus, Juliet and Lassiter rush there, where Shawn reveals a secret door to the basement. When they get down there it appears that a Petrovich's shadow is reaching for a gun, so Lassiter turns and shoots him twice in the chest. Lassiter goes to personally tell all the families affected by Petrovich that he's gone for good, but Shawn realizes that Petrovich had a scar on his hand, and the shooter didn't. Juliet rushes in and tells Shawn and Gus that Petrovich had died hours earlier from a drug overdose, and Shawn deduced it was rats that made it look like Petrovich was reaching for a gun. Shawn asks if there were signs of restraints on Petrovich's arms, and there was. Shawn realized that Petrovich's killer, and the shooter, was Mr. Salamatchla, the father of one of the kids who overdosed because of Petrovich, and they rush off to save Lassiter. They arrive to see Lassiter at gunpoint by the father, at the son's grave. Salamatchla was upset because they only put Petrovich away on gun charges, and he was already out. He wanted revenge on the broken system, and for his son. Shawn tried to channel his younger self, who had a perfect throwing arm (once), and threw Psych's phone at the father. It totally missed, but distracted him long enough for Lassiter to break free and arrest the man.
The title refers to the disruption to a player's natural flow or rhythm which can send them into a slump. It is generally viewed as a primarily psychological phenomenon, often with no clearly identifiable source or direct cause.