A bit abstract, but I like it...
OK, here it goes...
Shots of a quiet town. Everyone is going about their boring, mudane daily schedules.
Shot of a man dressed in all black sneaking around an alley. He approaches a lever and pulls it down.
The entire town goes black and white. People are shocked, confused, and panicked. The town floods out of their homes, offices, etc. and fonto the streets in search of the cause of the B&W color change.
One man finally wanders down the alley and finds the lever. He turns it back on and everything goes back to normal. Everyone celebrates. The man raises his arms in triumph and walks away.
The "man in black" sneaks out into the alley again, turns the lever off, rips it off the wall, and takes it with him. The scene changes to black and white. Celebrating people look confused, look to the sky, fade out.
Hmmm... maybe it's a little cheesy, but with a sick music track in the background (starts out slow and minor, gets more and more intense, when the color comes back on it reaches a climax and modulates into a major key, and suddenly goes back to the mood in the beggining when the color is turned back off) it might turn out pretty cool. If you find or write a good song to fit the film, I don't think you'd need any other audio. I'm all about short films with hidden underlying messages, and I think this one would fit the bill.
Hope this helps!