YMMV / Murder on the Leviathan

• Complete Monster: Marie Sanfon is a skilled, ruthless and utterly self-serving serial criminal. She encourages her lover Charles Renier, son of a deposed rajah, to look for his father's hidden treasure. When the clue to the treasure's location, a shawl, is found, Marie, with some help from Charles, murders ten people, including two children, just to steal it. Later, Charles, at her prompting, commits two more murders aboard the Leviathan whenever the shawl's safety is threatened. Finally, when Marie's attempts to frame another passenger fail, she decides to Leave No Witnesses and urges Charles to steer the ship, with a thousand passengers and crew, onto rocks. Her calm doesn't falter when Charles takes all the blame as the plan is foiled or when Charles is killed by the French detective who also wants the treasure. Marie only goes berserk when Erast Fandorin throws the shawl into the sea, proving that she cares for no one and nothing but money.