help me out finding this book

I once read a great shapeshifting werewolf book back in the late 80's or early 90's. I do not remember it's name or author. I had checked it out of the library. It was a fiction novel. It was NOt a horror werewolf type book. The book was fantastic.
The story was something like this: werwwolves were shapeshifters who lived among us and were all over the world. Each year they would all meet and travel to there hidden kingdom in some secret place--i thin it was in the northern hemisphere-somewhere like Greenland ? Their kind had a king and queen and when they were in their secret land they could become wolves freely and run and mate and hunt. I remember the main characters were brothers and sisters of the royal family. That's about all i can remember. anybody out there read a book like this?