It's only human nature to brace for the worst when being called out on something you did, but you may be misreading the situation. The reason why a superior or potential client wants to talk to you about a certain episode is that they want to get your version of events. This is all part of a vetting process where they will decide if you'll get the job, assignment, or promotion. Be forthright and transparent. You've nothing to hide, explain, or apologize for. In fact, your play-by-play telling of how things unfolded will quickly smooth out the inconsistencies and quell any doubts they might have.