detector detective

I look up to a black mass that has formed above me, a product of my imagination and blurred vision. The mass slowly grows, blacker, darker, and deeper than the rest of my surroundings, already shadowed by the absence of moonlight or streetlamps. Swimming in the black is a small green light. Green means go. Go where? Follow the small flicker of light into the unknown darkness? Then again, this isn't a metaphor; it's only a smoke detector telling me I'm not on fire (yet.)