A military mission, a woman's desire...What could Christophe, the mighty warrior of Poseidon, and Fiona Campbell, a prim Scottish artist who designs children's fairy tale books by day, and by night a notorious jewel thief who goes by the name "The Scarlet Ninja" have in common? Answer: "Siren", a legendary gem that Fiona plans to steal. It is rumored to be worth millions, but to Christophe it is priceless. In addition, "Siren" is one of the lost stones of the Trident of Poseidon. And a terrible evil can destroy them both. It takes two to break into the Tower of London, so Christophe and Fiona team up to commit the crime of the century. And when passion burns their intentions and clouds their common sense, they realize that they are not the only ones hunting for the priceless gem. A dark force follows them and threatens to destroy their trust in each other with revenge, betrayal and secrets from the past.