July 2010, Montreal, Canada. 25-year-old Sophie Maisterre, a fashion illustrator, is feeling anxious about the summer vacation that lies ahead. No plans, no boyfriend, no fiancé. She then hears about SWITCH.com, an accommodation exchange website. Sophie miraculously finds a duplex in Paris with a view of the Eiffel Tower.
Her first day there is idyllic. The following morning, she is woken by the cops. A headless corpse has been found in the room next door. Sophie no longer has any way of proving that she isn't Bénédicte Serteaux, the owner of the apartment. She's caught in a trap.
Not only has Sophie changed apartments, she has become a whole other person with a whole new destiny.