Possible twist: The mom wanted to get rid of the kid and planned this from the beginning. It'd look like an accidental death and she'd be free of the burden of having to raise a child. Or maybe the kid was adopted and she just learned his biological parents passed away and were loaded so she killed the kid for the inheritance money? And maybe she kidnapped the kid to begin with, and the parents were looking for him but were already old so they died of old age, or something.It definitely has potential and there's a lot of ways you could go with it. I'd be interested in seeing more. As is though it's weak.