Cursed painting

Markus and Sara are a well-known couple in Paris’ artistic circles. He is a wonderful painter, she is a beautiful woman, taking her first steps as a novelist. They belong to the capital’s bohemia. Their life is extraordinaly colourful. They spend their days in parisian coffee shops and unending banquets. They are a part of a vivid group of writers, artists and filmmakers, living a full and decadent lives. Their personalities are as fascinating. Sara is a bit introverted, and walks her own path. She can always be spotted in the crowd thanks to her gorgeous chestnut hair. Markus, on the contrary, is a hot-tempered persona. His tough and dominating personality were often a source of numerous brawls, that he would start while intensely drunk.
Yesterday, an opening of a new exhibition of Markus’ paintings, most of which depict Sara. As a group of friends of this mad couple, you wouldn’t miss such an occasion. Unfortunately something went wrong. The couple didn’t show up. They don’t answer calls or text back and nobody knows where they can be. An entire day has passed, and still there hasn’t been a sign of life from them. You are worried. You remind yourselves that you are in possession of a key to Markus’ workshop. You go straight there. What had happened?