It sounds like a more complicated marriage of Black Jack and Baccarat. Natasha's interest is piqued, gaze narrowing as she follows along with the explanation.

"How do the values change while the cards are in play? Is a card positive and negative at the same time?" Natasha spears a few pieces of her fruit cup and eats them carefully off of her fork while she listens.

Food is secondary to the card game being described.