Showing Free Fall by Robert Crais

Elvis Cole is just a detective who can't say no, especially to a girl in a terrible fix. And Jennifer Sheridan qualifies. Her fiancé, Mark Thurman, is a decorated LA cop with an elite plainclothes unit, but Jennifer is sure he's in trouble - the kind of serious trouble that only Cole can get him out of.

Five minutes after his new client leaves the office, Cole and his partner, the enigmatic Joe Pike, are hip-deep in a deadly situation as they plummet into a world of South Central gangs, corrupt cops and conspiracies of silence. And before long, every cop in the LAPD is gunning for a pair of armed and dangerous killers - Cole and Pike.