This note contains spoilers for the book.

One of his four Hugo-winning novels.

This is one of his best. It's the story of an actor hired to double for the top politician in the solar system; but not a normal situation of using a double, in this case it's much worse, because it turns out the actual politician has been kidnapped.

And the first challenge he has to face is being adopted into a Martian nest.

I presume this benefits considerably from Heinlein's experience in real political campaigns. At least, it all sounds entirely believable.