In Act 1 it appears that this is going to be no more than a straightforward take on the old film classic GASLIGHT, but it quickly evolves into a tale with ample twists and turns of its own. I will say that I guessed the penultimate twist well before the story got there (I realized immediately that, unlike all the other "evidence" of Sylvia trying to drive Andrea crazy, all of which was seen and corroborated by Murray, no one but Andrea saw and spoke to Chris in the graveyard). But the very last revelation, just before the end, did indeed take me by surprise, and that's the fun of this kind of tale. Believability doesn't enter into it--the only question is whether the story can stay at least one step ahead of the listener, and for me, at least, this one succeeded.

The altered-painting notion, by the way, was probably inspired by "The Cemetery," the first story in Rod Serling's popular TV-movie NIGHT GALLERY, which had aired only a few years before (and which was the pilot for the early-70s TV series).

Good choice!