She was forced to flee Russia after the revolution.
Series 3 Edit
She barely speaks to Thomas, but is intrigued with his ability to carry out assassinations for the Crown.
It is revealed that Tatiana is to take a look at the vehicles in the Lanchester Factory that Thomas has prepared for the Russians.
At the Shelby Charity Foundation Dinner, Tatiana informs Thomas that the sapphire necklace Grace Shelby is wearing is "cursed by a gypsy", right before Grace is shot by an assassin.
"Can you do it? Can you kill?" — Tatiana to Thomas Shelby.