Mary open the door a bit to see who it is, only to see no one. She wonder if she didn't imaginate the knock.
She then open the door wider, thinking that they probably left something on her porch, only to find nothing and still no one. She go outside on the front yard to scan the area and see if anyone had just step out of her yard, no one again.
In the end, Mary would just turn to go back inside. But then, she noticed a few wet drops has fallen on her walkway, going from the now-closed front door to her. She feel a wet sensation on of her vagina. Seem like it still leaking cola.
A small breeze has blown, making Mary shivers for a bit. Remembering that she is outside wearing nothing more than bathrobe, she tighten it and grab the door handle.