TED-Ed: Can you solve the secret assassin society riddle? | Alex Rosenthal

In a high-stakes poker game, players are either assassins or victims. Assassins swap a card with their signature card to signal readiness. A drone monitors the game but is disabled before revealing shared cards. Analysis of the rules and card suits helps identify the assassins. The agent is revealed as a traitor, and the only victim is saved.

How does the protagonist realize that one of the players is a victim?

What is the identity of the protagonist's partner, and what role do they play in the game?