The episode opened with the CSI team investigating the death of journalist Denise Baines, who had died of liquid sarin poisoning outside a club. An employee at the club recalled how he'd seen another woman (Ashira) getting sick and vomiting before paying him to let her cut the line to get a cab, with the team recognizing that Ashira had also been exposed to the sarin and was now potentially at risk of dying of the effects.
Frank Tripp and Samantha Owens tracked Ashira down to an abandoned building, where Frank found her crying out for help, seemingly having trouble breathing from the poisoning. But as Frank tended to Ashira, he noticed her purse was filled with money, causing him to realize something was amiss. As Frank reached for the bag, however, Ashira turned heel by disabling Frank's gun and beating him with a baton, attempting to reach for a canister that fell from her purse when Frank grabbed her leg before kicking Frank and trying to flee. However, Ashira was subsequently subdued when Samantha arrived and struck her with her pistol.
Ashira was later questioned by Frank and Samantha, assuring Frank not to be embarrassed about her dismantling his gun so easily and telling Samantha to "take her pick" when she asked her for her real name, as several different passports were found in her purse. As for Denise, the evil Ashira confessed that she poisoned her by injecting liquid sarin into her eyedrops while she was in the club's bathroom, with her own non-fatal poisoning coming as a result of getting some drops of the substance on her hand when Denise nearly caught her in the act. When asked by Frank for the person who paid her, Ashira confirmed Frank's theory that she was a professional hitwoman and refused to name her client, and remorselessly stated she would take life in prison when Samantha warned her that was what she was facing if she didn't cooperate. With that, the handcuffed Ashira was taken away, with the episode's progression revealing she was paid by corrupt lawyer Darren Vogel to kill Denise due to her having uncovered his history of blackmailing former clients to help bolster his cases.
- Katrina Law also appeared on Chuck as the evil Alexis White.