"You scream, and you run"

Okay, so my first "Stranger Danger" conversation with Sydney did not go particularly well. It started out slow enough, and calm enough, but having exhausted the logic, Sydney quickly turned to the paranoid.
Suddenly, I'm being asked, what if the stranger is bigger than Daddy, or stronger? What if the bad guy kills Mommy and Daddy and she has no one to run to and she only cries? What if the stranger is faster than her and catches her? What if she can't scream loud enough? What if another family gets confused and tries to take her?
These are, on the surface, incredibly valid questions. Coming from a sobbing four-year-old though, they can only be satisfactorily answered by the information that: no one is stronger than Daddy, no one is faster than Mommy and Daddy, and Mommy and Daddy will never be away from you. Also, this is exactly why Mommy and Daddy hold your hand everywhere we go.
My goodness, she almost had me in tears a few times, with her little brain coming up with all these awful scenarios that are MY NIGHTMARE, but that I had to explain away as impossible, lest I have a hysterical child on my lap all night. And while the last thing I want is for her to be a frightful child, I'm somewhat impressed that the talk did sink in a bit, as well as pleased that she may just hold my hand whenever we leave the house until she's 30.