Cyril is an international criminal and smuggler, and the employer of Kelli Lin.
Cyril was a member of a foreign extortion ring primarily based in Prague. Kelli Lin, a former Olympic gymnast, was committing robberies to help feed her recently born child, Kai. When she was caught, the extortionists found her and offered her a place on their team. They kidnapped Kai and forced Kelli to begin committing more robberies using her speed and agility. She had to continue robbing things until a debt was paid off.
Following the robbery of a painting at a museum exhibition, Kelli brought the painting to Cyril at a bar where she would regularly meet with him. Cyril informed her that for her debt to be paid off, she'd need to perform one more heist. This was the robbery of an artifact known as the Gutenberg Bible, which was being shipped out of town that night.
Kelli's robbery attempt was foiled by Sameen Shaw, who was on her trail following the museum robbery. Cyril called Kelli, who told him that she didn't get the Bible. Cyril ordered her to find it and reminded her what she was playing for: he opened up a video chat with Kai on it, leading Shaw to realize that Kelli needed to be helped.
Reese, Finch and Shaw began learning more about Kelli: it was believed that decoys sent as distractions during robberies were being murdered afterwards, but Kelli was unaware of this and realized that Cyril was the one responsible. Eventually, Kelli was able to steal the Bible and bring it to Cyril. Finch took Interpol agent Alain Bouchard outside the bar to listen in on the conversation and learn the truth about Kelli.
Kelli placed the Bible in front of Cyril and demanded that she be done with her life of crime and get her daughter back. Cyril said that she would only be done with jobs when he said so, and opened up the video chat, only to see the criminals guarding Kai get beaten by Reese. Shocked, Cyril attempted to shoot Kelli but was instead shot in the leg by Shaw, who was sitting off to the side. Cyril was arrested and Kelli was reunited with her daughter.