Medical Mystery

 is a quest in Fallout: New Vegas.

Quick walkthrough
The easiest way to complete this quest is to simply wait, hidden, inside the medical tent starting at ~1:00 in the morning. Slightly before 3:00, a private will enter, crouched, and attempt to steal the supplies. Depending on your Speech level, you have a number of options in dealing with the situation.

You can also pickpocket the empty Hydra (the clue) from Private Stone, any time of the day, and report him to Dr. Richards.