A mysterious depiction of masked revellers at the Venice carnival hangs in the college rooms of Oliver's old professor in Cambridge. On this cold winter's night, its eerie secret is revealed by the ageing don. The dark art of the Venetian scene, instead of imitating life, has the power to entrap it. To stare into the painting is to play dangerously with the unseen demons it hides, and become the victim of its macabre beauty...