Artist Descending a Staircase

In 1972 an elderly avant garde artist is murdered, leaving his two friends suspecting each other. To reveal why, successive scenes flashback toward the 1920s and then progress back to 1972. Each of the three was infatuated with Sophie. Before she tragically went blind she fell in love with one of them after viewing his picture in a gallery. Which artist Sophie loved has been a bone of...