Wow. Impressive doesn't begin to cover it. I was expecting something reminiscent of Harlan Ellison's For I Have No Mouth and I Must Scream or The Matrix, but this one had several intriguing surprises. I will be running this.
Minor suggested change: have the painting show wolves hunting someone. Actually, you could show a hunt with all the details, making it just a pretty show... until they get into the painting, and become a show themselves. Finally, when (if) they get out, a heap or two of old, dry bones could be ejected with them... as a final warning. Go to Comment
The party wakes up in an inn around a table with wine goblets near at hand. They have forgotten all that happened the last day. As they seek to find the truth they come in contact with a man that gives them a job which pays quite nicely.
When they have finished with this rather dubious assignment they are invited to dinner by the the man...