Muggle-Born Year 1

Four friends Ruby, River, Rio, and Star believed they were normal tweenagers. On the last day of school, however, each receive their Hogwarts Letter in the mail. There is a catch-there have been no muggle borns in Hogwarts for over a decade. Can the quartet deal not only with thr bullying and 'mudblood' talk, but also a new evil slowly but surely arising?