She was portrayed by Katherine Boecher.
Tatiana helped free her boyfriend Anton Poldark from his imprisonment by sending in some henchmen to stage a car accident, and escape via helicopter. The brilliant plan worked and she awaited his arrival in a warehouse, and they both share a kiss. He complains of his imprisonment to Tatiana, but she reminds him he was in there for only 4 hours.
Later, she is on a computer tracking down the location of the buyer of their oil supply through a corrupt file Stockholm.GBH. When Poldark is disappointed of some clothes she brought him to wear, Tatiana tells him he could go shop some himself, which he supplies that he is the most wanted man in America, and cannot shop at a JC Penney's. Focusing on the mission, she tells him someone has downloaded the file, but it will take her awhile to track down the exact location.
She eventually finds the location and tells Poldark the good news. He tells Tatiana to bring some men with her and to leave no survivors. Tatiana arrives at the house as the men dig through furniture, rip pillows, and open up cereal boxes. Tatiana discovers the house is the home Poldark's worst enemy, Chinese Intelligence Agent Bob Ho, and then informs Poldark, who shoots his cellphone upon hearing it. Then Tatiana calls Poldark on his landline phone, and Poldark orders her to find Ho. When Tatiana tells her men that must locate Bob Ho, they informed that he is the house next door, where he is staying while watching his neighbor and girlfriend, Gillian's, children while she is taking care of her injured father.