Imagine stepping into a dark crime scene, looking for clues and trying to get inside the mind of a twisted criminal. Sparse piano motifs, ambient and rhythmic sound design, etc. Creates an unsettling mood great for murder mystery, criminal behavior, etc.
A tense and dark action / sci-fi / thriller underscore. Dark pads and twitchy, ethereal soundscapes, with action thriller style drum / percussion parts. Think horror / mystery / science fiction / dark drama. Can also be for very edgy sports footage.