Eric Ambler 
Charter To Danger [PDF ebook] 

Vincent Flavius, a millionaire industrialist, charters a cabin cruiser owned by Ross Barnes. Flavius is on the verge of engineering yet another sensational financial coup. Embarkation is set for Cannes, but that is where the trouble begins. Shock after shock follows a strange encounter Barnes has with a girl in a dingy cafe. Murder and kidnapping follow., along with a dangerous chase which brings the S uret e Nationale into swift action.