Treachery! is the first expansion to Professor Pugnacious' Portfolio of Perils, Pugilism, and Perfidy-the Card Game of Victorian Combat.

It focuses on Failure-both making opponents lose, and avoiding being forced to fail. It introduces a new class, the Traitor, who benefits by making the other players fail in their endeavors, a new mechanic, Stealth, which lets you play cards facedown to surprise your opponents, the game's first Mastermind-a new kind of Finale-and a host of new purchasable cards for the Main Deck, and new enemies for the Adversary Deck.