Take one high-school reunion being held on a floating oil rig in the process of being converted to a vacation resort, and hosted by a classmate that no one seems to remember. Add a poorly coordinated group of mercenaries being paid to assault said oil rig, some of whom are former terrorists -- from opposing sides. And include the (involuntary) participation of a just-retired police detective who can't seem to avoid running into evidence of Very Bad Things happening in the neighborhood and offshore.
And the dark humor is great... from the first paragraph when I read about "liquidised mercenary raining splashily down" on Connor, and thought to myself, Huh? Is that what I think I just read? Yup. "He reached up reluctantly and wiped the gore from his eyelids..." Not for the squeamish. But if you can appreciate black humor, this book will have you laughing in your chair.
One Fine Day in the Middle of the Night, by Christopher Brookmyre
Author Christopher Brookmyre's Web site - look under Books for the first three chapters online!