In Montreal, the unemployed fashion designer Sophie Malaterre is shown a website, switch.com, where it is possible to switch houses with a stranger for vacation. Sophie seeks an apartment in Paris nearby the Eiffel Tower that belongs to B├®n├®dicte Serteaux and they change apartments. Sophie arrives in Paris on Saturday morning. The next morning, policemen break in the apartment and arrest Sophie while she is having a bath. Detective Damien Forgeat interrogates Sophie believing that she is B├®n├®dicte and she learns that a beheaded body was found in her room and all evidence of her life has been deleted.
