From his offices in Switzerland, Russian Igor Lipovsky is engaged in a vast and profitable gunrunning operation with Africa. The French government wants to hinder the activities of the arms dealer and sends a team to sink one of his ships heading for Angola with a load of illegal weaponry. Lisa, Brisseau, Loïc, Tony and Raymond are professionals: they carefully set up their cover, plan all their moves meticulously, and carry out orders without asking questions. Perhaps they should. The code-name of the mission is "Janus"; and just like with the ancient deity, there are two opposite faces for every aspect of the operation: the objective of the French government, the role of each team member, the presumed friend and the assumed foe...

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 Bénédicte 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 Bénédicte and she learns that a beheaded body was found in her room and all evidence of her life has been deleted.

Málaga, southern Spain. Seven men, divided into four cars, set off with a large drug shipment towards Creil, a city near Paris; a routine mission that will be complicated by a fatal sequence of events.

A Parisian criminal gang fall apart after challenges to the gang's leader lessen his influence.