Manly Wade Wellman is one of the forgotten greats of American fantasy. His tales of John the Balladeer are far and away his most famous work, though in the decades before he gave us John he wrote tons of other stories. These included everything from the occult investigator John Thunstone to singleton stories like this one.
In 'The Golgotha Dancers', an unnamed art fancier finds a truly gruesome painting in a museum, planted there by some creepy character. He ends up taking it home where he and a lovely lady neighbor both find out that this is truly living art -- art that wants them to become part of itself.
The story is short but just long enough to set up a situation, present the people involved, and give us a clever yet very logical resolution. It's very different from Wellman's later work but it's still a fine piece of writing, made all the better for being free. Try it out, and you may well find yourself interested in finding more of his delightful fiction.