This was a good short. Loved the moment she placed all the pics together of the jigsaw, some good suspense there.
wow I did not see that ending coming at all. She's a nutter. Pretty funny.

Quoted Text EXT. THE OLD HOUSE - NIGHT

EXT. OLD HOUSE - NIGHT is fine, no need for 'the' at all.

Quoted Text She smiles in satisfaction, then sighs. MARGOT So easy. Where�s the challenge?

Kinda contradictory. She's satisfied and smiling yet bemoans the lack of challenge. Surely the lack of challenge means its an unsatisfying puzzle? Besides, the line isn't needed.

Quoted Text Someone has slipped it through the mail slot.

Unnecessary.

Quoted Text MARGOT Well, who could of... She grins a bit. The challenge of a jigsaw is irresistible to her. MARGOT Oh, well. No sense in waiting.

Again, unnecessary. You've already done a good job conveying her love of puzzles.

The use of 'LATER' isn't something that particularly bothers me but I've read that its a no-no.

As she's putting together this puzzle I really feel the tension. You've done an excellent job filching pretty much all the suspense you can out of the situation!

Sadly I hate where it goes after that. I wouldn't have had the man in the trench coat be an attacker with an axe, but her Husband playing a cruel joke on her. Just my preference though.  

Total 50/50 for me. Hated half, loved half. You have a knack for the suspense but overall I felt the twist/alternate take on the UL felt incredibly tacked on and so comical it undercuts the rest of the script.

Nice setup. It's hard not to feel for a lonely old lady.

I was a bit sceptical when I read -

'Margot turns around, to see the man in the trenchcoat staring back at her.'.

My initial reaction was that if you added a bit more build up, this could've been a good place to end it. I was certain it was gonna go downhill from here with a couple of pages of the man swanning around inside the house. Glad to find out I was wrong. It just kept getting better and ended at a gruesome, well thought out climax. Great work.

Entire title page is to be plain 12 point courier, title all caps only, please.
LOL! This was very nice!  
Mercifully brief and a delight to read.
Very Bradbury-ish.
Will make a great short film for a producer, very economical in resources - aside from the pile of limbs.

Writing style:
Good.

Dialogue:
Fine. I loved the last line. Brilliant.

Character:
Didn't care for her. You need to make me.

Story:
I like how the victim became the predator. What I didn't like is that the suspenseful moments was abrupt. I didn't get to enjoy them. Also the mystery of the puzzle wasn't solved in a graceful manner. A scene she was curious why it looked like her kitchen, the next moment there is man by the window.

Overall:
I wish you had put more meat on the mystery and suspense bones. It could have turned this into a gem.

Good luck and well done.

A tight, effective piece, cool concept.

I did anticipate, as the scene was unfolding, that the jigsaw was going to be of Margot doing the puzzle with some disconcerting revelation. It just had to be really, it’s the nature of these spooky stories. Thus, any tension created, in what was a well written scene, was greatly neutered by its inherent predictability.

However, the script had a final sting in the tail that I didn’t see coming which gave it a much more satisfying impression while subverting my presumptions about what direction I thought it would go. Suitably demented and depraved too!