A janitor walks through Fox's office building, cleaning up the desks. She asks Fox if he's working late again, and then screams when she realizes that he's been killed by strangulation with a piano wire.
The coroner works on Fox as Frank and Lt. Bosslady observe. She says that his blood alcohol content was .13, so he didn't feel much. Frank says that based on Fox's attire, he was having an after-work cocktail with someone he knew. Lt. Bosslady figures that Fox got tipsy and let his guard down, and then he was killed. Stu bursts in with a hair sample from Fox's office, and the hair has no pigment. Frank realizes that it probably belongs to Lloyd, who had a piano at his house. He adds that Lloyd sued Turney and Fox got the suit thrown out. Lt. Bosslady thinks that's motive enough for her.
Stella continues to listen to the tone that killed Turney. John walks in. Stella asks if he forgot to sleep, since he looks like crap. John says he was up all night doing research on ragweed, trying to figure out where it grows, and he found out that it's all over the world. Stella explains that they linked Lloyd to Fox's murder, so they don't need to match the sound anymore. John gets an idea and strips the tone from the audio tracks to hear the ambient noise of the room where it was recorded. Stella notes that it's a perfect A. John flashes back to when he was in the recording studio and noted that the pitch at the center of the room was an A.
John goes to the recording studio alone. He creates some feedback using an amp. Randi shows up and asks what he's doing. John says that she recorded feedback from the speakers, slowed it down, and played it at the concert. Randi denies it. John says she used that amp and microphone, because the settings are still on key, and then Fox figured it out, so she killed him too. Then, she broke into Lloyd's house and took the piano wire. Do real cops tell the criminals how they committed their crimes? Randi says she has a rule about not sleeping with the musicians. John guesses that she made an exception. Randi says that Turney was "extra ordinary," but I'm guessing that she means "extraordinary." Randi says that success changed him, and John guesses that the groupies started showing up. Randi says she couldn't trust Fox. John says he has to call the police. Randi seems relieved that it's over, but then she turns and runs out the door.
John tries to chase her, but he's locked in the studio. Um, throw a chair through the giant window? He tries a few doors before trying to break the window, with no luck. He figures out the correct pitch he will need to play to shatter the glass, and then puts some liquid in a coffee mug to create the right pitch and amplify it. The window shatters. Meanwhile, out in the hallway, Randi is furiously punching the elevator button. Why not take the stairs? John runs into the hallway just as the elevator arrives, but it's full of furniture, so Randi takes off. John calls Frank on his cell phone while giving chase. He realizes that she climbed up the fire escape to the roof. John gets up there just in time to see Randi run in a door to the stairwell and lock it behind her. John runs to the edge of the roof, where he sees two pulleys and a wire attached to it. He looks down to see that the wire is attached to a couch on the ground. John yells down to ask what kind of couch it is, and then uses it as a counterweight to zip down to the ground. Hey, when he stepped off the wire, shouldn't the couch have come crashing down to the ground? He catches Randi just as she runs out the door.