Timekeepers - It's Just About Time

After a strange wizard shows up at the Blackstones' doorstep, the life of Emerald and Saphire completely changes. They suddenly are supposed to travel back in time to fix another of fate's horrible mistakes. So the two sisters get sent to Hogwarts in the 1970's and have to change quite some things there, but there are many problems they need to solve in order to return back home safely...

Hey, this is my first fanfiction, and also my first english story, so please excuse and rather correct possible mistakes. Also I'm not very familiar with the geographical aspects of London/England, so please excuse mistakes in that point as well.
But now, have fun with the story!