I'm desperately trying to find the title of a book I read years ago. I believe it was written in the 80s(?). I picked it up from a 2nd hand shop about 20 years ago.
It was about a race of giant lizards (possibly aliens) that shape-shift into humans. They bred with humans and lost their ability to do it. The story follows a man who witnessed his family killed by one of the last ones of its kind and is trying to find it.
All I can remember is that it has lumps on its spine when it is in human form and it runs a high-end business.