Circle of Assassins — Steven Rigolosi

Five desperate strangers answer an ad that promises to help them rid an unwanted person from their life.  A criminal mastermind named “A” makes each of them a provocative offer via an advertisement in The Clarion, a community newspaper published on Manhattan's Upper West Side: Murder a complete stranger chosen by a fellow assassin, and in return have a stranger murder your chosen target.

How many of those who answer the advertisement will accept A's offer to join the circle of assassins, in which anonymity is guaranteed?  Which of the killers will succeed in their plots?  Who is A, and will he or she end up dead or alive?