The Long Cosmos
Terry Pratchett and Stephen Baxter conclude their long Earth series with The Long Cosmos (see 11/24/15 for entry about previous book in series). In this tale a message of interstellar origin has been received all across the long Earth, a message that says simply join us. How people react to the message and the consequences of their actions make up the book.
The book, while definitely not a stand alone, is an enjoyable read that I would recommend. If you haven’t read the long Earth series pick up the first title, The Long Earth, and get started.