Time Stoppers

Because I am reading for the MSBA shortlist I am reading far more fantasy than I normally like.  I will get to the realistic fiction soon...

Annie and Jamie have both had pretty horrible experiences.  Annie has gone from one foster home to another and this newest one in Bar Harbor, Maine is pretty terrible.  Jamie has lived with his dad and grandmother in Bar Harbor his whole life but they are awful to him - always threatening to eat him.  One night Jamie discovers that his grandma and dad are not normal - in fact they are monsters - literally.  As Annie and Jamie both try to escape their situation they are rescued by Eva - a dwarf and taken to a magical world where Annie discovers she is a time stopper and Jamie finds out that his dad and grandmother are trolls and he is... well, no one knows what he is.

Can Annie and Jamie help save their new village of Aurora from the evil that threatens?  

This is the first in a series and as such ends on a bit of a cliff hanger.  Not too bad.  For a title of time stoppers there is really only one instance of time stopping.  I had hoped for more...