I should have read and reviewed this much sooner, but I've been alternating between busy and sick for weeks now. And lazy.
The comments will actually be pretty short, though. It's fun to read a good heist, and the writing itself came through fairly solid. I will say, though, that it feels silly for the combination to be written down or added into the paintings, unless someone is specifically testing or messing with the group (which you indicated might be the case). I'm interested to see how this goes.
I'll try to have more comments (and sooner) for the next piece.