Please take a look at the following quotation:
"... the cat had been missing for three days now..."
I have not as yet been made aware that the past perfect continuous can be connected to the present through a time expression, that is, for three days now. On the contrary, I've always thought that it categorically finishes before another past event.
If I were to express those thoughts, I would certainly have used the present perfect continuous:
the cat has been missing for three days now.
Please let me know why did the author use the past perfect continuous, and by the by, what is its use implication, what do you think of the cat's status: found or still missing?