Översättning - Japanska-Engelska - 「いいか、ついてきてはならんぞ！

This text is from a video game and I can't seem to translate it on my own. My reading comprehension is getting better, but by listening is not good. Without kanji, I have a difficult time reading. If you could provide me with a breakdown of each word and particle, that would really help me learn for the future. (american english)

A more polite version would be:
良いか、付いて来てはならないよ

But a gruff male would say 「ならんぞ」at the end.

To be perfectly frank, without a context, I don't who (or what) you're not "supposed to follow", because Japanese doesn't need to specify the subject (as you probably know already). ^_^