NOTE: This is an easily missed two-step achievement!
Episode 2: Get Tannen!
The first step of this achievement can be missed at the beginning of the chapter. While Marty is hiding behind the bar looking for ways to distract the goons and rescue Artie, you will need to find the hidden code beneath the bar (right of the hidden alarm switch). If you do not do this, you can not find the secret exit at the end of the chapter. Once you interact with the code, continue the story as normal.
The second step is near the end of the chapter. Once you have completed the scene where Matches brings in the stick of dynamite, Tannen takes the hidden exit via the roulette wheel secret. You are then able to go to the roulette wheel and pick the last option (scroll all the way down) which is "Bet on 7, 23 & 30". The achievement should pop as you exit.