Fallon Jamison, out for a run in Central Park, is accosted by a stranger calling her "Charlotte." She eludes him, but on her run, she spies a flyer of a missing woman named Charlotte Fiske who looks exactly like her.

Fallon, recently divorced, has been anticipating a summer in New York, exploring the city and taking a theater class. However, her world is suddenly turned upside down. Detectives arrive at her door, and insist on taking her to the police station.

The DNA proves that Charlotte Fiske is her own identical twin, although she has grown up as an only child. The detectives suspect that her husband, Anthony Fiske, a prominent New York surgeon has done away with her. After determining her identity, they enlist her in a sting to find out what happened to Charlotte.

When the scheme goes awry, both sisters are caught in a deadly trap by vicious kidnappers.

As they face ever-growing danger, even the threat of murder, they are forced to use all of their ingenuity and courage to attempt an escape.