The story follows the efforts of detective Cassie Maddox to determine the circumstances surrounding the death of Lexie Madison, a young woman who is her doppelgänger.

[1] The dead woman not only resembles Cassie but also was living under an alias the detective used in an earlier undercover assignment.

A senior police officer, Frank Mackey, convinces Cassie to impersonate the dead woman to investigate her death and to discover who she really was.

[2] The Irish Independent praised the "elegance and insight" of French's writing and described the book as "a brilliant thriller, beautifully written.

"[4] In a more critical vein, Janet Maslin of The New York Times commented that French "could have achieved the same effects much more succinctly in a more tightly edited version of this same story.