It mean single
If you mean the first series, then the book is A Dangerous Path. If you mean the second series, then the book is Twilight. Lastly, if you mean the third series, then the book is Long Shadows.
If you mean books, then there's 7 books in all. If you mean series there is only 1.
Stages mean a single step,degree, or series
it is website with tv series on it
To be touching in an unbroken series
A series of little farts.
Is a series of number
the number in the series
I presume you mean a 'series interview'. This means you will have a series of interviews, most likely with different individuals or different or the same individuals.