From the introduction:
You are top-of-the-line security robots made by EcoPrague Incorporated with a very innovative and relatively new system where you store solar energy to power you up for upwards of six hours into the night. However, you and your other robot buddies were rented out by a very rich company a week before that was possible. Worst of all, you were assigned to guard what many consider a teenage rite of passage: prom.
Making things worse is that you and your friends have a very limited supply of solar energy. By working together, you and your friends must find a way to prevent the prom from being ruined. Not only that, but you also cannot be seen by the teenagers or anyone lacking the knowledge of your existence, lest they freak out at your appearance and figure that something’s up.
This is Prom. It cannot be ruined. You must protect it at all costs. That is what you robots call: The Prom Directive.