Martingale Trophy in Syberia 3
During a discussion, use an irrefutable argument that you obtained by exploring.
How to unlock Martingale
See Crime and punishment.
This can also be unlocked by speaking with the female protestor at the automaton statue before speaking with the mayor in Valsembor (Lobbyist) or by looking at Katerina's photo album before speaking with her in Baranour (I am legend).