Stu (Stu!), John, and Frank examine the club where Turney died. Stu is looking at some amateur video shot by high school kids at the concert. Frank wonders what could have caused the seizure. John points out that there aren't any strobe lights or magnetic interference from the amps that could have triggered it. Stu comments that the video quality is poor even for a bootleg as some static lines roll up the screen. John notices that the static appears just before Turney's seizure. John starts checking out the soundboard for loose connections and such, and he notices one line that deviates from the rest. He follows the line and finds a device mounted under a nearby shelf. John asks the sound guy to turn that channel up, and Frank says he doesn't hear anything. John says that's why it's the perfect murder weapon.
Stu examines the device and pulls out a tape. Frank asks how a tape with no sound could kill someone. They should just rename Frank "Audience Stand-In" and be done with it. John explains that it can cause damage. He has Stu play the tape, and then shows Frank that it's lower than twenty hertz, which is lower than humans or dogs can hear. Frank asks how it's a murder weapon. John explains that the sound vibrations knocked out Turney's anti-seizure device and triggered a seizure. Stu points out that it's like how an MRI will make a pacemaker go crazy. Frank isn't buying the theory.
Rachel talks to Lt. Bosslady at the cop station. She explains why John's theory holds water. Stella observes and asks John if Rachel is a friend of his. Stella is looking hot in a short skirt and tall boots. Go, Stella! John says they met on a plane. Stella's like, "I wish she'd go back on that plane and get out of here." John and Rachel continue explaining how the device worked. Stella says that the military's been researching it for years to create "an ammunition-free lethal weapon." Frank says that the three of them (John, Rachel, and Stella) should start their own club with "personalized pocket protectors." Should you really be making fun of the very people who have solved pretty much every criminal case in the past few months? Stella plays a sample of the sound, which has been sped up so they can hear it; Rachel thinks it sounds mechanical. John lists off some of the things that could create the sound. Lt. Bosslady says that if they find out how it was recorded, they might be able to find out where it was recorded. Frank adds that they might be able to figure out who recorded it as well. Lt. Bosslady asks if Stella can figure it out, and Stella says she'll run it through some database. Frank says he buys that the sound was a murder weapon now. Lt. Bosslady wants to focus on suspect and motive, and asks if Turney had any enemies, and who would know him well enough to know about his epilepsy. Frank promises to look into it.