We open at a benefit for a Santa Barbara community outreach program that helps at-risk youths get out of gangs. The honoree is the charity's founder, Deacon Jones. Also there is his Financial Director, Tina, a former gang member and alum of the program, who is in charge of the festivities as well as handling all donations and pledges.
Shawn and Gus are excited because Gus' old friends, Joon (from the High Top Fade Out episode) and Drake are in town. Deacon Jones has asked their a cappella group, Blackapella, to perform at the benefit. We learn Deacon helped Drake and Joon when they were kids. Drake and Joon were headed for the gang life, but Deacon helped them stay away from it. We also learn Shawn has weaseled his way into performing with Blackapella and is suffering from stomach butterflies. Blackapella's performance goes great, but after their third group bow, Shawn collapses in pain.
At the hospital, we learn Shawn's appendix burst. Lassiter, Juliet, Henry, Drake and Joon show up. Shawn is touched, until he learns that after he left, Deacon was shot. Deacon is brought in unconscious, attended by cops, doctors and Jimmy Brigham, Deacon's head of security.
All Lassiter has at this point is a description of a black SUV with partial plates fleeing the scene. The Chief wants Deacon's shooting to be the SBPD's #1 priority and that Brigham is going to keep an eye on Deacon.
Drake and Joon want Psych on the case, but Shawn says he and Gus can't due to Shawn's incapacitation. Outside the room, though, Drake tells Gus, "You know you're helping us investigate this." "I know," replies Gus. Back in the room, Henry tells Shawn, "You know they're investigating this." "I know," replies Shawn feeling jealous and left out.
Back at the SBPD, McNab hands over a list of black SUV's that may or may not have been at the scene of the shooting. Gus, Drake and Joon show up and tell Lassiter they are here to help, but Lassiter isn't having it.
Lassiter learns that a gang, the Rolling Ones, has been harassing Deacon. Their leader, Lil Sis, is in jail doing five years for armed robbery, but is still calling the shots. Lassiter is against Gus, Drake and Joon helping until Gus explains that Lil Sis is in the same prison as Marlowe. If she helps get information it could earn Marlowe an early release. Lassiter brightens and has a change of heart.
Lassiter meets in the prison yard with Marlowe who's having trouble getting close to Lil Sis, but has an idea. "Just remember, this is for us," she whispers, then slugs Lassiter in the face and is dragged off by guards. Lil Sis watches, impressed.
Later, in the prison visiting room, Marlowe has definitive proof Lil Sis isn't behind Deacon's shooting, but she did reveal that someone in Deacon's organization is skimming money.
Lassiter theorizes that Deacon found out who it was, and they tried to take him out. Gus gets a call from Shawn, who busts him for investigating without him. Gus tells Shawn about the skimming lead.
Shawn flashes back to Deacon's second in command, Tina, who handles all the charity's money. Lassiter will go to the community center to question Tina, while Gus, Drake and Joon will go the charity's boot camp in case she's there. "Not without me, you won't," Shawn says. "You're not investigating any more unless I'm with you."
Gus, Drake and Joon arrive at the boot camp with Shawn, who is on Gus' iPad via FaceTime. They witness Tina taking money from a lock box in the office, and follow her to a cabin in the woods, where they confront her and she pulls a gun on them.