Thinking about this in a D&D-esque context.
So if the "telegraph" is the presence of bodies, or scorch marks, or whatever, then the "follow through" should be getting caught in the trap. The reaction might be trying to detect and disarm the trap, or Dimension Dooring to the other end of the corridor, or similar. It would make sense for there to be some cost to this (so that it's not just a puzzle-solving guessing game), either a resource cost (more common in D&D) or a "story"-type cost (less common in D&D).
In the social context, the "telegraph" might be warnings of a traitor in the ranks. The follow through would be the act of treachery. The reaction might therefore be (eg) purging the ranks, or perhaps trying to identify the traitor. Insight skill looks like it could be helpful for that second sort of reaction.
