As part of an ad campaign for Niels Arden Oplev's upcoming neo-noir thriller crime film Dead Man Down, NYC-based marketing firm Thinkmodo decided to see what New Yorkers would do if they happened to stumbled onto a crime in progress — namely, a murder.

The agency set up a camera inside a nondescript New York City elevator, and filmed the reactions of unsuspecting marks as they encountered a man strangling another man to death with an extension cord.

Not surprisingly, many passers-by chose to bolt rather than take any immediate action, though some tried to help, and at least one took the matter into his own hands.

But the last guy... well, not to spoil the ending, but let's just say, it's doubtful anything any of Dead Man Down's "dark secrets" could be as chilling as what he chose to do.

[H/T: Geekologie]