'Blood Work' - that's what Terry McCaleb used to call his job at the FBI. Eight weeks ago he was a dead man, but now someone else's heart is keeping him alive. Then a newspaper report of his brush with death brings him an unwanted visitor. Graciela Rivers reveals to McCaleb that the anonymous donor of his heart was her murdered sister. Knowing that he lives because of a cold blooded killing, McCaleb takes the moribund investigation on. Nothing about the seemingly random killing makes sense but McCaleb is a tenacious man and little by little he realises that someone is watching his every move - someone who has killed before and will kill again...