In Chicago at the Fidelity Mutual Bank, Mr. Jarvis chats briefly with the teller, Laura. Outside, three black-clad figures emerge put on sonic protection equipment and masks, park outside, and go into the bank. As Mr. Jarvis calls his wife, one of them starts to open their coat and a blast of sound is emitted.
Myka is outside Warehouse 13 talking to someone on her phone while inside, Peter plays table tennis against a mirror image of himself from a mirror belonging to Lewis Carroll. Artie is in his office with Leena and determines there's been another bank robbery in Chicago. The computers go briefly on the fritz and then recover. Someone starts hacking into the computer form an external server, breaking through the firewalls. Artie tries to trace the hacker but they easily deflect his efforts. Pete comes in and realizes his last forward pass is coming in. He runs outside to warn Myka, who is talking to her mother about her dad's upcoming retirement party. As Myka says she won't be there, Pete tells her to duck. Artie tells them about the third Chicago robbery and informs them they're going to Chicago.
At the bank, Pete and Myka wait to get the security tape. A customer drops a book, causing echoes throughout the room. As Pete wonders if Artie is crankier than usual, an FBI team comes in led by agent Bonnie Belski. She takes charge of the investigation and knows all about Bering and Lattimer. Belski knows about how Myka screwed up in Denver. She refuses to cooperate with them and goes, with Pete watching her every step.
Pete calls Dickinson in Washington, and Dickinson manages to clear them with the FBI and get Belski's cooperation. Meanwhile, Myka talks to her mother and refuses to be guilted into coming to her father's retirement party. Pete notes that if his dad was alive, he'd go to see him.
While Artie tries to track the hacker, Pete moves into Belski's office and sets up dioramas of the robbery sites. Each robbery occurred during rush hour and they have six hours until the next rush hour. Belski doesn't know how the robbers got the victims to just hand over their money and wonders if Pete knows, but he insists he doesn't.
Myka calls Artie, who complains that she bypassed him and went to Dickinson. He insists the agents have to go through him. Myka runs the video from the last robbery and he notices something inside one robber's coat. The tapes are all silent and none of the witnesses remember anything. Artie notes that strobe lights can induce amnesia and Myka spots Jarvis on the tape making a call on his cell phone. While she looks up the name so Artie can get a number, Artie determines where the hacker is.
Myka gets a recording of the cell call and brings it to Belski's office. As she waits for Belski, she points out to Pete that Belski knows what she's doing to attract his attention. Belski brings the bank teller, Laura in, and play back the recording. Laura goes into a trance, a blissful look on her face. When they stop the recording, Laura doesn't remember what happens and says she had a feeling of being loved.
The agents brief Artie, who figures the sound is a limbic trigger connecting to the victims' pleasure centers. Someone has to hear it "live" to be effected the first time, and then it leaves a sense memory. While Artie sorts out the song for its unique tone, Pete comments it sound like his dad's favorite song, Center of My Soul by Eric Marsden. Artie confirms that the mesmerizing song's chromatic DNA matches the song that Peter remembers. He also determines that Marsden lives in Chicago, making him a likely suspect. With four hours until rush hour, the agents head out. Meanwhile, Artie explains to Leena that he tracked the hacker to the office computer belonging to Daniel Dickinson.
Pete and Myka approach Marsden's house, which is in bad shape. A woman, Jessilyn, answers the door and explains that she was once Marsden's back-up singer. She lost her voice and has been Marsden's caretaker for five years. His wife left him and he hasn't talked to his daughters in year. Marsden is catatonic and dying of liver cancer. Myka talks to Marsden, who compliments her on her voice. Pete checks the room and notices a photograph of Marsden's daughter. He starts playing the piano and Marsden reacts, saying that it contains everything. He blanks out again and outside, Jessilyn explains that Marsden went through a variety of music , looking for a key to the human heart. Now, Jeff Canning, owner of Windy Lake Records, owns all of Marsden's music. Jessilyn thinks that Marsden went catatonic after he lost his own music, and she suggests they talk to Canning. As they go, Pete brings up her father again and she explains her party is having party for her father. He suggests that she go but she explains that her father was an overbearing bully.
The agents go to the record company and wait while the secretary, Stephanie, talks on the phone and puts on perfume. Both agents notice subtle clues that the company is on the ropes financially. They meet with Canning who shows them the storage room where he keeps all of Marsden's music. He claims that Marsden's music is out of fashion but an anonymous buyer has recently expressed an interest in buying it. Some of Marsden's experimental is there, and Canning claims it's unmarketable. He blames Jed Fissel, Marsden's engineer, who got Marsden to experiment with new age music. Last Canning heard, Fissel was driving a cab years ago. He insists that there is no unpublished Marsden music and he has everything. Stephanie comes in to tell her boss that she's leaving after a half-day of work.
Later, Stephanie goes to see Fissel and warn him that the Secret Service is onto them. The third member of their team arrives: Jessilyn. She says that the situation has changed and they need more money.
Myka tries to figure out the pattern to the robberies while discovering that Fissel disappeared six months ago. Belski calls Pete and tells him they're running a stakeout on a specific bank based on one of the few banks that is clear during rush hour. Pete is doubtful and Myka says he should stay with her, but Pete thinks it's best to go with Belski. Myka gives in and tells him to go.
Artie breaks into Dickinson's office and hacks his computer password.
Myka calls her mother apologize and a waitress drops a tray. She connects the echo to the echo she heard in the bank and realizes what all three sites had in common.
Artie starts going through Dickinson's files and Myka calls, explaining that the stone walls of the bank amplify the song's effects. She has Artie check the banks that fit the pattern. Dickinson comes in and Artie uses a camera, taking a picture of him that turns Dickinson into a life-photo. He then comes up with two bank addresses.
As Stephanie and Jessilyn drive to the next robbery, Jessilyn assures Stephanie that everything will be okay.
As Belski and Pete watch the bank, Belski asks what he does and Pete dodges the question. She asks about Myka and wonders if her history in Denver bothers him. Belski explains that there are rumors that Martino, a married man separated from his wife, was having an affair with Myka. Artie calls and tells Pete what Myka has learned and where she is.
Myka arrives at the bank wearing earplugs as the robbers use Marsden's song to steal the money. She chases them back to their van and manages to capture Fissel, but Stephanie and Jessilyn escape. Pete and Belski's team arrive and Myka explains what ties the robberies together. Myka knows that at least one of the other robbers was a woman.
Artie packs up and restores Dickinson to normal, then accuses him of hacking the Warehouse 13 computer. Dickinson insists that he had nothing to do with the computer hack.
As Belski's team bring Fissel in to FBI headquarters, Pete apologizes for screwing up. He notices the acoustics of the building and realizes they're the same as at the banks. He tells Myka to put in her earplugs. Jessilyn and Stephanie emerge from the elevator and play Marsden's music. Everyone but Myka is immobilized and she's only partially protected. She manages to grab Fissel and shove her cell phone into his coat pocket before Stephanie gets him away.
Artie and Dickinson go over Dickinson's computer and realized that the hacker ran the breach through Dickinson's office. Dickinson asks to help but Artie refuses. Artie gets a call from Myka and takes it privately. She explains she needs Artie to track the cell phone and that Pete is still partially under the music's effect. Artie ends the call and Dickinson tells him that he's staying no matter what. Artie has no choice but to let him stay.
Myka tells the still bedazzled Pete that Artie is tracing her cell phone. He comments on her perfume and she says she isn't wearing any. Pete realizes that the perfume is Stephanie's and it got on Myka when they struggled over Fissel. Artie calls and gives them the cell phone's locations.
The agents go to the house and find Jessilyn. She insists it was never about the money. She shows them to a room where Jed is playing the piano while Stephanie listens to it with her father, Eric Marsden. All of Marsden's music is there. Jessilyn explains that they stole the bank money to buy back Marsden's music from Canning. With it, Marsden has something to hold onto. Now Stephanie can have her father back for the short time he has left. Myka suggests they call the FBI but Pete says that the record with Marsden's music is their problem. He figure it's Belski's problem to track down the robbers. Pete gets the record while Myka goes outside and calls her mother and asks to speak to her father.
Artie takes apart the computer and prepares to trace the hacker. There's an electrical arc and Artie has a brief flash of memory. He then finds himself floating in a void with a man screaming to make it stop. Artie finds himself back in the real world as Dickinson wonders what happened.