Kate Priddy was always a bit neurotic, but after an ex-boyfriend kidnapped her and nearly ended her life, her bouts of anxiety began exploding into full-blown panic attacks. When Corbin Dell, a cousin in Boston, suggests the two temporarily swap apartments, Kate agrees, hoping that time away in a new place will help her overcome the past traumas of her life. But at Corbin's grand apartment on Beacon Hill, Kate makes a shocking discovery: his next-door neighbor has been murdered, and Kate finds herself caught in a vise of voyeurism, betrayal, and manipulation.