Yuri Komarov was a scientist from Russia who went rogue and tried to sell a deadly isotope.
Komarov was Russia's top nuclear scientist, but he went missing. APO got word that he had gone rogue and was going to sell a deadly and unstable isotope called Aurine-12 on a train heading from Belarus to Latvia.
To stop the sale going down, Sydney went into Komarov's private carriage, holding an equally as legitimate looking ticket, and staying in the room. She flirted with the scientist, changing into nightwear and asking how she looked as well as feigning stupidity towards his business. She asked to see what he was working on after he told her that he was a chemist. As he had opened his briefcase (which Sydney needed him to do himself as it had a self-destruct feature installed if anyone else tried to break into it) she knocked him out and took the vial to safety.