Meg Gardiner: Mission Canyon [2004] paperback

Evan Delaney, novelist and legal go-fer, is dressed as Diana Ross in order to crash a fancy-dress party and serve a summons, when she hears that Franklin Brand is back in town. Brand is the hit-and-run driver who sentenced Evan's lover Jesse to life in a wheelchair, and killed his best friend. Since the accident, Brand has been avoiding justice overseas; but if he's back, Evan and Jesse are determined to get him, helped by the dead boy's brother Adam. Brand had been a high-flier in Mako Technologies, a cyber-security firm, and this is where Evan starts looking. She quickly uncovers evidence that Brand was embezzling funds, and that Adam's brother knew all about it. So maybe that hit-and-run wasn't an accident at all?Then the policeman investigating is killed, and Adam and Jesse both come under suspicion. The plot has more twists, thrills and spills than a white-knuckle ride, and is complicated by the confused emotions of the main parties involved: Jesse feels a survivor's guilt; Adam resents the fact that Jesse is alive while his brother died. But there are more corpses - including a near miss for Evan herself - to come before the bad guys are finally brought to book.