This experiment was designed to help students improve the critical thinking skills that are required to analyze and discuss the results of an organic chemistry experiment in an effective manner. The initial objective indicated in the prelab handout for this puzzle experiment was the synthesis of methyl 4-bromobenzoate using the Fischer esterification. Before beginning the experiment, however, students were informed that someone, acting as a "mole", might have sabotaged their experiment so that different results would be obtained. Their new objective was to perform the experiment, determine if any sabotage had occurred, and, if so, identify the changes that were made to the reagents as well as the person who was responsible for these modifications. Using the results from the experiment, spectroscopic data for the reagents provided by the instructor, and melting point values from chemical reference materials, students were able to complete this goal and become more adept at analyzing the outcome of a synthetic organic chemistry experiment. The Fischer esterification is found in many laboratory manuals and the series of carboxylic acids used for this procedure are safe and relatively inexpensive, so the experiment should be adaptable to most organic laboratory curricula.