Catch the Saint — Leslie Charteris

On an errand of mercy for an elderly neighbor, Simon Templar meets a distraught but beautiful damsel in distress. It seems she is missing her brother…and someone else is missing a Rembrandt. Soon the Saint discovers the two are connected, and he's on the trail of “The Masterpiece Merchant.” In Philadelphia, the Saint meets a lovely young heiress at a charity ball, only to discover that another member of the party is a leading figure in organized crime.