Hailed by Douglas Preston as "a master storyteller," Joshua Corin returns with another white-knuckle thriller featuring ex-FBI agent Xanadu Marx. And this time, payback comes with a price tag.   They call themselves the Serendipity Group, a charitable organization that helps victims take revenge on those who've wronged them. But when the group's hit list leaks, the hunters become the hunted--and two innocents are caught in the crossfire.   A pair of newlyweds are waylaid in Atlanta after a bad storm disrupts their flight to Paris. They are stuck in a dingy airport hotel room--until a stranger insists the happy couple take his lavish suite. But the man's kindness is a ruse: They are being used as bait, and soon find themselves prisoners of a maniac with a hacksaw--all because of a list of thirteen people marked for execution.   Ex-FBI agent Xanadu Marx doesn't know how her name ended up on the list, but she'll be toast if she doesn't take herself off it. Now a civilian on parole after a career-killing mistake, Xanadu Marx supposedly has three days to live, and the question isn't whether she has an enemy gunning for her, it's which one. But when two wide-eyed newlyweds may have become collateral damage, Xana realizes that there are some sins that can't be forgiven.   Don't miss any of Joshua Corin's electrifying Xanadu Marx thrillers: COST OF LIFE * FORGIVE ME * AMERICAN LIES