A fundraising event for the science department at a local university is cut short when all of the guests fall ill. Catherine ambushes Grace's former roommate, dancer Monica Jessup, in the hopes of getting help with her investigation. Monica is hesitant so Catherine leaves her card. The team suits up in hazard gear to investigate. They discover three bodies remaining from the party, a university lawyer and an administrator and the COO of a defense contractor. Maxine snaps at Beau when he suggests removing the protective suits. Max, Serena, and Beau interview the victims at the hospital. Sonya finds no chemicals but alcohol in the dead victims' systems. Monica brings Catherine a watch that Grace was given while serving drinks at a private poker room. Monica says Grace was asking too many questions. The FBI charges into the morgue and takes control of the bodies. Beau suggests Sonya necropsy the rat that also died. Monica stole evidence from the poker game. Allie proposes hydrogen-peroxide poisoning. The FBI has let go of the crime scene. Folsom finds a pattern of malfunctioning electronics around the scene. Beau finds a direct-energy weapon which causes Havana Syndrome. Folsom hypothesizes that lawyer Woodall was targeted by Professor Morrow. While interrogating Morrow, Max sees grad student Luther Canal faking symptoms of his injuries. Jodi tells Catherine that her suspect, Mikel Koslov, has fled to Belarus. Canal admitted he used the weapon to stop Woodall from making a deal for it with the defense contractor Corrigan, with the other partygoers collateral damage. He also pointed out an invention of Beau's that was made into a weapon. Catherine tells Monica that she used to work at a similar club. Catherine heads to Belarus. The FBI takes the weapon and the lab's related work. Beau kept the power pack.